Arthur Neville Chamberlain (18 March 1869 – 9 November 1940) was a British Conservative politician who served as Prime Minister of the United Kingdom from May 1937 to May 1940. Chamberlain is best known for his appeasement foreign policy, and in particular for his signing of the Munich Agreement in 1938, conceding the Sudetenland region of Czechoslovakia to Nazi Germany. When Adolf Hitler continued his aggression, Britain declared war on Germany on 3 September 1939, and Chamberlain led Britain through the first eight months of the Second World War.

After working in business and local government and after a short spell as Director of National Service in 1916 and 1917, Chamberlain followed his father and older half-brother in becoming a Member of Parliament in the 1918 general election at age 49. He declined a junior ministerial position, remaining a backbencher until 1922. He was rapidly promoted in 1923 to Minister of Health and then Chancellor of the Exchequer. After a short Labour-led government, he returned as Minister of Health, introducing a range of reform measures from 1924 to 1929. He was appointed Chancellor of the Exchequer in the National Government in 1931. When Stanley Baldwin retired in May 1937, Chamberlain took his place as Prime Minister. His premiership was dominated by the question of policy towards the increasingly aggressive Germany, and his actions at Munich were widely popular among Britons at the time. When Hitler continued his aggression, Chamberlain pledged Britain to defend Poland's independence if the latter were attacked, an alliance that brought Britain into war when Germany attacked Poland in 1939.

Chamberlain resigned the premiership on 10 May 1940, after the Allies were forced to retreat from Norway as he believed a government supported by all parties was essential, and the Labour and Liberal parties would not join a government headed by him. He was succeeded by Winston Churchill and remained very well regarded in Parliament, especially among Conservatives. Before ill health forced him to resign, he was an important member of Churchill's War Cabinet, heading it in the new premier's absence. Chamberlain died of cancer six months after leaving the premiership.

Chamberlain's reputation remains controversial among historians, with the initial high regard for him being entirely eroded by books such as Guilty Men, published in July 1940, which blamed Chamberlain and his associates for the Munich accord and for allegedly failing to prepare the country for war. Most historians in the generation following Chamberlain's death held similar views, led by Churchill in The Gathering Storm. Some recent historians have taken a more favourable perspective of Chamberlain and his policies, citing government papers released under the Thirty Year Rule.

Chamberlain was born in a house called Southbourne, in the Edgbaston district of Birmingham, England. He was the only son of the second marriage of Joseph Chamberlain, who later became Lord Mayor of Birmingham and a Cabinet minister. Joseph Chamberlain had had another son, Austen Chamberlain, by his first marriage. Neville Chamberlain was educated at Rugby School. Joseph Chamberlain then sent Neville to Mason Science College in central Birmingham. Neville Chamberlain had little interest in his studies there, and in 1889, his father apprenticed him to a firm of accountants. Within six months, he became a salaried employee.

In an effort to recoup diminished family fortunes, Joseph Chamberlain sent his younger son to establish a sisal plantation on Andros Island in the Bahamas. Neville Chamberlain spent six years there, but the plantation was a failure, and Joseph Chamberlain lost £50,000.

On his return to England, Neville Chamberlain entered business, purchasing (with assistance from his family) Hoskins & Company, a manufacturer of metal ship berths. Chamberlain served as managing director of Hoskins for 17 years, during which time the company prospered. He also involved himself in civic activities in Birmingham. In 1910, he fell in love with Anne Cole, a distant relative by marriage, and the following year married her. The two had a son and a daughter.

Chamberlain initially showed little interest in politics, though his father and half-brother were in Parliament. During the "Khaki election" of 1900 he made speeches in support of Joseph Chamberlain's Liberal Unionists. The Liberal Unionists were allied with the Conservatives and later merged with them under the name "Unionist Party", which in 1925 became known as the "Conservative and Unionist Party". In 1911, Neville Chamberlain successfully stood as a Liberal Unionist for Birmingham City Council for All Saints' Ward, located within his father's parliamentary constituency.

Chamberlain was made chairman of the Town Planning Committee. Under Chamberlain's direction, Birmingham soon adopted one of the first town planning schemes in Britain. The start of war in 1914 prevented implementation of his plans. In 1915, Chamberlain became Lord Mayor of Birmingham. As a Lord Mayor in wartime, Chamberlain had a huge burden of work, and he insisted that his councillors and officials work equally hard. He halved the Lord Mayor's expense allowance, and cut back on the number of civic functions expected of the incumbent.

In December 1916, the Prime Minister, David Lloyd George, offered Chamberlain the new position of Director of National Service, with responsibility for coordinating conscription and ensuring that essential war industries were able to function with sufficient workforces. However, his tenure was marked by conflict with Lloyd George, and in August 1917, having received little support from the Prime Minister, Chamberlain resigned. The relationship between Chamberlain and Lloyd George would be one thenceforth of hatred.

Chamberlain decided to stand for the House of Commons, and was adopted as Unionist candidate for Birmingham Ladywood. After the war ended, a general election was called almost immediately. He was elected with almost 70% of the vote and a majority of 6,833. At age 49, he is still the oldest Parliamentary debutant to later become Prime Minister.

Chamberlain threw himself into Parliamentary work, begrudging the times when he was unable to attend debates and spending much time on committee work. In March 1920, he was offered a junior post at the Ministry of Health by Bonar Law on behalf of the Prime Minister, but was unwilling to serve under Lloyd George. Chamberlain was offered no further posts during Lloyd George's premiership, and when Bonar Law resigned as party leader, Austen Chamberlain took his place as head of the Unionists in Parliament. Unionist leaders were willing to fight the 1922 election in coalition with the Liberals, but on 19 October, Unionist MPs held a meeting at which they voted to leave the Coalition. Lloyd George resigned, as did Austen Chamberlain, and Bonar Law was recalled from retirement to lead the Unionists as Prime Minister.

Many high-ranking Unionists refused to serve under Bonar Law, to the benefit of Chamberlain, who rose over the course of ten months from backbencher to Chancellor of the Exchequer. Bonar Law initially appointed Chamberlain Postmaster General. When Sir Arthur Griffith - Boscawen, the Minister of Health, lost his seat in the 1922 General Election and failed to win a by-election in March 1923, Bonar Law offered the position, within the Cabinet, to Chamberlain. Two months later, Bonar Law was diagnosed with advanced, terminal throat cancer. He immediately resigned, and was replaced by Chancellor of the Exchequer Stanley Baldwin. In August 1923, Baldwin promoted Chamberlain to the position of Chancellor of the Exchequer. Chamberlain served only five months in the office before the Conservatives were defeated in the 1923 general election. Ramsey MacDonald became the first Labour Prime Minister but the Labour government fell within months, necessitating another general election. Chamberlain narrowly defeated Labour candidate Oswald Mosley (who later led the British Union of Fascists). Believing he would lose if he stood again in Ladywood, Chamberlain arranged to be adopted for Birmingham Edgbaston, a much safer seat which he would hold for the rest of his life. The Unionists won the election, but Chamberlain declined to serve again as Chancellor, preferring his former position as Minister of Health.

Within two weeks of his appointment as Minister of Health, Chamberlain presented the Cabinet with an agenda containing 25 pieces of legislation he hoped to see enacted. Before he left office in 1929, 21 of the 25 had passed into law. Chamberlain sought the abolition of the elected Poor Law Boards of Guardians, which administered relief and which in some areas were responsible for rates. Many of the Boards were controlled by Labour, and had defied the government by distributing relief funds to the able bodied unemployed. In 1929, Chamberlain brought in legislation to abolish the Poor Law boards entirely. Chamberlain spoke in the Commons for two and a half hours on the second reading of the Bill, and when he concluded, he was applauded by all parties. The Bill passed into law.

Though Chamberlain struck a conciliatory note during the 1926 General Strike, in general he had poor relations with the Labour opposition. Future Labour Prime Minister Clement Attlee complained that Chamberlain "always treated us like dirt", and Chamberlain wrote in April 1927, "More and more do I feel an utter contempt for their lamentable stupidity." His poor relations with the Labour Party later played a major part in his downfall as Prime Minister.

Baldwin called a general election for 30 May 1929, which resulted in a hung parliament, with Labour holding the most seats. Baldwin and his government resigned, and Labour leader Ramsay MacDonald took office. In 1931, the MacDonald government faced a serious crisis, as the May Report revealed that the budget was unbalanced, with an expected shortfall of £120 million (about £6 billion today). On 24 August 1931, the Labour government resigned and MacDonald formed a National Government, supported by most Conservative MPs. Chamberlain once more returned to the Ministry of Health.

After the 1931 general election, in which supporters of the National Government (mostly the Conservatives) won an overwhelming victory, MacDonald designated Chamberlain as Chancellor. Chamberlain proposed a 10% tariff on foreign goods, with lower or no tariffs on goods from the colonies and the Dominions. Joseph Chamberlain had advocated a similar policy, "Imperial Preference". On 4 February 1932, Neville Chamberlain laid his bill before the Commons. Chamberlain concluded his address by noting the appropriateness of his seeking to enact his father's proposal. At the end of the speech, Sir Austen Chamberlain walked down from the backbenches and shook his brother's hand. The Import Duties Act 1932 passed Parliament easily.

Chamberlain presented his first budget in April 1932. He maintained the severe budget cuts that had been agreed to at the inception of the National Government. Interest on the war debt had been a major cost in each budget. Chamberlain was able to reduce the interest rate on most of Britain's war debt from 5% to 3.5%. Between 1932 and 1938, Chamberlain halved the percentage of the budget devoted to payment of interest on the war debt.

Chamberlain hoped that a cancellation of the war debt owed to the United States could be negotiated. In June 1933, Britain hosted the World Monetary and Economic Conference. The Conference came to nothing, however, when US President Franklin Roosevelt sent word that he would not consider any war debt cancellation. By 1934, Chamberlain was able to declare a budget surplus, and restore many of the cuts in unemployment compensation and civil servant salaries he had made after taking office. He told the Commons, "We have now finished the story of Bleak House and are sitting down this afternoon to enjoy the first chapter of Great Expectations."

Defence spending had been heavily cut in Chamberlain's early budgets. By 1935, faced with a resurgent Germany under Hitler's leadership, he was convinced of the need for rearmament. Chamberlain especially urged the strengthening of the Royal Air Force, realising that Britain's traditional bulwark, the English Channel, was no defence against air power.

In 1935, MacDonald stood down as Prime Minister, while Baldwin became Prime Minister for the third time. In the 1935 General Election, the Conservative dominated National Government lost 90 seats from the massive majority of 1931, but still retained an overwhelming majority of 255 in the House of Commons. During the campaign, deputy Labour leader Arthur Greenwood had attacked Chamberlain for spending money on rearmament, stating that the rearmament policy was "the merest scaremongering, disgraceful in a statesman of Mr. Chamberlain's responsible position, to suggest that more millions of money needed to be spent on armaments".

Soon after the 1936 Abdication Crisis, Baldwin announced that he would remain until shortly after the Coronation of King Edward's successor George VI. On 28 May, two weeks after the Coronation, Baldwin resigned, advising the King to send for Chamberlain. Sir Austen did not live to see his brother's final "climb ... to the top of the greasy pole", having died two months earlier.

Upon his accession, Chamberlain considered calling a general election, but with three and a half years remaining in the current Parliament's term, decided to wait. At age 68, he was the second oldest person in the 20th century (behind Sir Henry Campbell - Bannerman) to become Prime Minister for the first time, and was widely seen as a caretaker who would lead the Conservative Party until the next election and then step down in favour of a younger man, with Foreign Secretary Anthony Eden a likely candidate. From the start of Chamberlain's premiership, a number of would-be successors were rumoured to be jockeying for position.

Chamberlain had disliked what he considered to be an overly sentimental attitude by both Baldwin and MacDonald on Cabinet appointments and reshuffles. Although he had worked closely with the President of the Board of Trade, Walter Runciman, over the tariff issue, Chamberlain dismissed him from his post, offering him the token position of Lord Privy Seal, which an angry Runciman declined. Runciman, a member of the Liberal National Party, was thought by Chamberlain to be lazy. Soon after taking office, Chamberlain instructed his ministers to prepare two-year policy programmes. These reports were to be integrated, with the intent of coordinating the passage of legislation through the current Parliament, the term of which was to expire in November 1940.

At the time of his succession, Chamberlain's personality was not well known to the public, though he had made annual budget broadcasts for six years, which, according to Chamberlain biographer Robert Self, appear relaxed and modern, showing an ability to talk directly to the camera. Chamberlain had few friends among his parliamentary colleagues, and an attempt by his Parliamentary Private Secretary, Lord Dunglass (later Prime Minister himself as Alec Douglas-Home) to bring him to the Smoking Room in the Commons to socialise with his colleagues ended in embarrassing silence. Chamberlain compensated for these shortcomings by devising the most sophisticated press management system employed by a Prime Minister up to that time, with officials at Number 10, led by his chief of press, George Steward, convincing members of the press that they were colleagues, sharing power and insider knowledge, and should espouse the government line.

Chamberlain saw his elevation to the premiership as the final glory in a career as a domestic reformer, not realising that he would be remembered for foreign policy decisions. One reason he sought the settlement of European issues was in the hope it would allow him to concentrate on domestic affairs.

Soon after attaining the premiership, Chamberlain obtained passage of the Factories Act 1937. This act was aimed at bettering working conditions in factories, and placed limits on the working hours of women and children. In 1938, Parliament enacted the Coal Act 1938, which allowed for nationalisation of coal deposits. Another major piece of legislation passed that year was the Holidays with Pay Act. Though the act only recommended that employers give workers a week off with pay, the Act caused the great expansion of holiday camps and other leisure accommodation for the working classes. The Housing Act 1938 provided subsidies aimed at encouraging slum clearance, and maintained rent control. Chamberlain's plans for the reform of local government were shelved because of the outbreak of war in 1939. Likewise, the proposal to raise the school leaving age to 15, scheduled for implementation on 1 September 1939, could not go into effect.

When Chamberlain became Prime Minister, relations between the United Kingdom and the Irish Free State had been strained since the 1932 accession of the new Irish Taoiséach (Prime Minister) Éamon de Valera. The Anglo-Irish Trade War, sparked by the withholding of money that Ireland had agreed to pay the United Kingdom, had caused economic losses on both sides, and the two nations were anxious for a settlement. The de Valera government also sought to remove the remaining ties between Ireland and the UK, such as ending the King's status as Irish Head of State. Chamberlain, as Chancellor, had taken a hard-line stance against concessions to the Irish, but having been persuaded that the strained ties were having effects on relations with other Dominions, sought a settlement with Ireland.

Talks had been suspended under Baldwin in 1936, but resumed in November 1937. De Valera sought not only to alter the constitutional status of Ireland, but to overturn other aspects of the Anglo-Irish Treaty, most notably the issue of partition, as well as ceding control of the three "Treaty Ports" which had remained in British control. Britain, on the other hand, wished to retain the Treaty Ports, at least in time of war, and to obtain the money that Ireland had agreed to pay.

The Irish proved very tough negotiators, so much so that Chamberlain complained that one of de Valera's offers had "presented United Kingdom ministers with a three leafed shamrock, none of the leaves of which had any advantages for the UK". With the talks facing deadlock, Chamberlain made the Irish a final offer in March 1938 which acceded to many Irish positions, though Chamberlain was confident that he had "only given up the small things", and the agreements were signed on 25 April 1938. The issue of partition was not resolved, but the Irish agreed to pay £10 million to the British. There was no provision in the treaties for British access to the Treaty Ports in time of war, but Chamberlain accepted de Valera's oral assurance that in the event of war, the British would have access. The agreements were attacked by Conservative backbencher Winston Churchill in Parliament for surrendering the Treaty Ports, which Churchill described as the "sentinel towers of the Western Approaches". When war came, de Valera denied Britain access to the Treaty Ports under Irish neutrality. Churchill railed against these treaties in The Gathering Storm, stating that he "never saw the House of Commons more completely misled" and that "members were made to feel very differently about it when our existence hung in the balance during the Battle of the Atlantic". Chamberlain, however, believed that the Treaty Ports were unusable if Ireland was hostile and deemed their loss worthwhile to assure friendly relations with Dublin.

Chamberlain sought to conciliate Germany, and make it a partner in a stable Europe. He believed Germany could be satisfied by the restoration of some of her colonies and during the Rhineland crisis of March 1936, had stated that "if we were in sight of an all-round settlement the British government ought to consider the question [of restoration of colonies]".

The new Prime Minister's attempts to secure such a settlement were frustrated because Germany was in no hurry to talk to Britain. Foreign Minister Konstantin von Neurath was supposed to visit Britain in July 1937, but cancelled his visit. Lord Halifax, the Lord President of the Council, visited Germany privately in November, and met with Hitler and other German officials. Both Chamberlain and British Ambassador to Germany Nevile Henderson pronounced the visit a success. Foreign Office officials complained that the Halifax visit made it appear Britain was too eager for talks, and Foreign Secretary Eden felt that he had been bypassed.

Chamberlain also bypassed Eden while the Foreign Secretary was on holiday, by opening direct talks with Italy, an international pariah for its invasion and conquest of Ethiopia. At a Cabinet meeting on 8 September 1937, Chamberlain indicated that he saw "the lessening of the tension between this country and Italy as a very valuable contribution towards the pacification and appeasement of Europe" which would "weaken the Rome – Berlin axis". The Prime Minister also set up a private line of communication with Italian Duce Benito Mussolini through the Italian Ambassador, Count Dino Grandi.

In February 1938, Hitler began to press the Austrian government to accept Anschluss or union between Germany and Austria. Chamberlain believed that it was essential to cement relations with Italy in the hopes that an Anglo – Italian alliance would forestall Hitler from imposing his rule over Austria. Eden, however, believed Chamberlain was being too hasty in talking with Italy and holding out the prospect of de jure recognition of Italy's conquest of Ethiopia. Chamberlain concluded that Eden would have to accept his policy, or resign. The Cabinet heard both men out, and unanimously decided for Chamberlain. Despite efforts by other Cabinet members to prevent it, Eden resigned from office. In later years, Eden tried to portray his resignation as a stand against appeasement (Churchill described him in The Second World War as "one strong young figure standing up against long, dismal, drawling tides of drift and surrender") but many ministers and MPs believed there was no issue at stake worth resignation. Chamberlain appointed Lord Halifax as Foreign Secretary in Eden's place.

In March 1938, Austria became a part of Germany in the Anschluss. Though the beleaguered Austrians requested help from Britain, none was forthcoming. Britain did send Berlin a strong note of protest. In addressing the Cabinet shortly after German forces crossed the border, Chamberlain placed blame on both Germany and Austria. Chamberlain noted,

It is perfectly evident now that force is the only argument Germany understands and that "collective security" cannot offer any prospect of preventing such events until it can show a visible force of overwhelming strength backed by the determination to use it. ... Heaven knows I don't want to get back to alliances but if Germany continues to behave as she has done lately she may drive us to it.

On 14 March, the day after the Anschluss, Chamberlain addressed the House of Commons, strongly condemning the methods used by the Germans to achieve the takeover of Austria. Chamberlain's address met with the approval of the House.

With Austria absorbed by Germany, attention turned to Hitler's obvious next target, the Sudetenland region of Czechoslovakia. With three million ethnic Germans, the Sudetenland represented the largest German population outside the Reich. Hitler began to call for the union of the region with Germany. Britain had no military obligations towards Czechoslovakia; France and Czechoslovakia had a mutual assistance pact. After the fall of Austria, the Cabinet's Foreign Policy Committee considered seeking a "grand alliance" to thwart Germany, or alternatively, an assurance to France of assistance if the French went to war. Instead, the committee chose to advocate that Czechoslovakia be urged to make the best terms it could with Germany. The full Cabinet agreed with the committee's recommendation, influenced by a report from the chiefs of staff stating that there was little that Britain could do to help the Czechs in the event of a German invasion. Chamberlain reported to an amenable House that he was unwilling to limit his government's discretion by giving commitments.

Britain and Italy signed an agreement in April 1938. In exchange for de jure recognition of Italy's Ethiopian conquest, Italy agreed to withdraw some Italian "volunteers" from the Nationalist (pro-Franco) side of the Spanish Civil War. The Nationalists by now strongly had the upper hand in this war, and completed their victory the following year. Later that month, the new French Prime Minister, Édouard Daladier came to London for talks with Chamberlain, and agreed to follow the British position on Czechoslovakia.

In May, two Sudeten German farmers, attempting to cross the border into Czechoslovakia without stopping for border controls, were shot by Czech border guards. This incident caused unrest among the Sudeten Germans, and Germany was said to be moving troops to the border. In response to the report, Prague moved troops to the German border. Halifax sent a note to Germany warning that if France intervened in the crisis on Czechoslovakia's behalf, Britain might not stand aside. Tensions calmed, and Chamberlain and Halifax were applauded for their "masterly" handling of the crisis. Though not known at the time, it later developed that Germany had had no plans for a May invasion of Czechoslovakia. Nonetheless, the Chamberlain government received strong, almost unanimous support from the British press.

Negotiations between the Czech government and the Sudeten Germans dragged on through mid-1938. They achieved little result, with Sudeten leader Konrad Henlein under private instructions from Hitler not to reach an agreement. On 3 August, Walter Runciman (by now Lord Runciman), travelled to Prague as a mediator sent by the British government. Over the next two weeks, Runciman met separately with Henlein, Czech President Edvard Beneš and other leaders, but made no progress. On 30 August, Chamberlain met with his Cabinet and Ambassador Henderson, and secured their backing, with only First Lord of the Admiralty Duff Cooper dissenting for his policy to pressure Czechoslovakia into making concessions on the ground that Britain was in no position to back up any threat to go to war.

Chamberlain realised that Hitler would likely signal his intentions in his 12 September speech at the annual Nuremberg Rally, and discussed with his advisers how to respond if war seemed likely. In consultation with his close adviser, Sir Horace Wilson, Chamberlain set out "Plan Z" — if war seemed inevitable, Chamberlain would fly to Germany and negotiate directly with Hitler.
Lord Runciman continued his work, attempting to pressure the Czech government into concessions. On 7 September, there was an altercation involving Sudeten members of the Czech parliament in the Czech city of Mährisch - Ostrau. The Germans made considerable propaganda of the incident, though the Prague government attempted to conciliate them by dismissing Czech police who had been involved. As the tempest grew, Runciman concluded that there was no point in attempting further negotiations until after Hitler's speech. The mission would never resume.

The final days before Hitler's speech on the last day of the Rally were spent amidst tremendous tension, as Britain, France, and Czechoslovakia all partially mobilised their troops. Thousands gathered outside 10 Downing Street on the night of Hitler's speech in Nuremberg. At last, the Führer addressed his wildly enthusiastic followers:

The condition of the Sudeten Germans is indescribable. It is sought to annihilate them. As human beings they are oppressed and scandalously treated in an intolerable fashion ... The depriving of these people of their rights must come to an end. ... I have stated that the Reich would not tolerate any further oppression of these three and a half million Germans, and I would ask the statesmen of foreign countries to be convinced that this is no mere form of words.

The following morning, 13 September, Chamberlain and the Cabinet were informed by secret service sources that all German embassies had been told that Germany would invade Czechoslovakia on 25 September. Convinced that the French would not fight (Daladier was privately proposing a three-Power summit to settle the Sudeten question), that evening Chamberlain decided to implement "Plan Z", and sent a message to Hitler that he was willing to come to Germany to negotiate. Hitler accepted, and Chamberlain flew to Germany on the morning of 15 September; this was the first time, excepting a short jaunt at an industrial fair, that he had ever flown. Chamberlain flew to Munich and then journeyed by rail to Hitler's retreat at Berchtesgaden.

The face to face meeting lasted about three hours. Hitler demanded the annexation of the Sudetenland, and through questioning him, Chamberlain was able to obtain assurances that Hitler had no designs on the remainder of Czechoslovakia or on the areas in Eastern Europe which had German minorities. After the meeting, Chamberlain returned to London, believing that he had obtained a breathing space during which agreement could be reached and the peace preserved. Under the proposals made at Berchtesgaden, the Sudetenland would be annexed by Germany if a plebiscite in the Sudetenland favoured it. Czechoslovakia would receive international guarantees of its independence which would replace existing treaty obligations, principally the French pledge to the Czechs. The French agreed to the requirements. Under considerable pressure, the Czechs also agreed, causing the Czech government to fall.

Chamberlain flew back to Germany, meeting Hitler in Bad Godesberg on 22 September. Hitler brushed aside the proposals of the previous meeting, stating "that won't do anymore". He demanded immediate occupation of the Sudetenland, and that German territorial claims in Poland and Hungary be addressed. Chamberlain objected strenuously, telling Hitler that he had worked to bring the French and Czechs into line with Germany's demands, so much so that he had been accused of giving in to dictators and had been booed on his departure that morning. Hitler was unmoved.

That evening, Chamberlain told Lord Halifax that the "meeting with Herr Hitler had been most unsatisfactory". The following day, Hitler kept Chamberlain waiting until mid-afternoon, when he sent a five-page letter, in German, outlining the demands he had spoken of orally the previous day. Chamberlain replied by offering to act as an intermediary with the Czechs, and suggesting that Hitler put his demands in a memorandum which could be circulated to the French and Czechs.

The leaders met again late on the evening of 23 September; a meeting which stretched into the early morning hours. Hitler demanded that fleeing Czechs in the zones to be occupied take nothing with them. He extended his deadline for occupation of the Sudetenland to 1 October — the date he had long since secretly set for the invasion of Czechoslovakia. The meeting ended amicably, with Chamberlain confiding to Hitler his hopes they would be able to work out other problems in Europe in the same spirit, and Hitler hinting that the Sudetenland fulfilled his territorial ambitions in Europe. Chamberlain flew back to London, stating "It is up to the Czechs now."

Hitler's proposals met with resistance, not only from the French and Czechs, but also from some members of Chamberlain's cabinet. With no agreement in sight, war seemed inevitable. The Prime Minister issued a press statement, calling on Germany to abandon the threat of force in exchange for British help in obtaining the concessions it sought. On the evening of 27 September, Chamberlain addressed the nation by radio, and after thanking those who wrote to him, stated:

How horrible, fantastic, incredible it is that we should be digging trenches and trying on gas-masks here because of a quarrel in a far-away country between people of whom we know nothing. It seems still more impossible that a quarrel that has already been settled in principle should be the subject of war.

On 28 September, he called on Hitler to invite him to Germany again to seek a solution through a summit involving the British, French, Germans, and Italians. Hitler replied favourably and word of this response came to Chamberlain as he was winding up a speech in the House of Commons, which sat in gloomy anticipation of war, and he informed the House of this in his speech. The response was a passionate demonstration, with members cheering Chamberlain wildly, and even diplomats in the galleries applauding. Lord Dunglass later commented, "There were a lot of 'appeasers' in Parliament that day."

On the morning of 29 September, Chamberlain left Heston Aerodrome (to the east of today's Heathrow Airport) for his third and final visit to Germany as Prime Minister. On arrival in Munich, the British delegation was taken directly to the Führerbau, where Daladier, Mussolini and Hitler soon arrived. The four leaders and their translators held an informal meeting, with Hitler stating that he intended to invade Czechoslovakia on 1 October. Mussolini distributed a proposal similar to Hitler's Bad Godesberg terms — in fact, they had been drafted by German officials and transmitted to Rome the previous day. The draft was debated by the four leaders, and Chamberlain raised the question of compensation for the Czech government and citizens, which Hitler refused to consider.

The leaders were joined by advisers after lunch, and hours were spent on long discussions of each clause of the Italian draft agreement. Late that evening, the British and French went to their hotels on the grounds that they had to seek advice from their respective capitals, while the Germans and Italians enjoyed the feast which Hitler had intended for all the participants. During this break, Chamberlain adviser Sir Horace Wilson met with the Czechs, informing them of the draft agreement and enquiring which districts were particularly important to them. The Munich Conference resumed about 10 p.m., and was mostly in the hands of a small drafting committee. At 1:30 a.m., the Munich Agreement was ready for signing, a ceremony delayed when Hitler discovered that the ornate inkwell on his desk was empty.

Chamberlain and Daladier returned to their hotel, and informed the Czechs of the agreement. The two Prime Ministers urged quick acceptance by the Czechs of the agreement, since the evacuation by the Czechs was to begin the following day. At 12:30 pm, the Czech government in Prague objected to the decision, but agreed to its terms.

Prior to leaving the Führerbau, Chamberlain requested a private conference with Hitler, which the German leader agreed to, and the two met at Hitler's flat in the city later that morning. Chamberlain urged restraint in the implementation of the agreement, and requested that the Germans not bomb Prague if the Czechs resisted, to which Hitler seemed agreeable. Chamberlain took from his pocket a paper headed "Anglo – German Agreement", which contained three paragraphs, including a statement that the two nations considered the Munich Agreement "symbolic of the desire of our two people never to go to war again". According to Chamberlain, Hitler interjected "Ja! Ja!" ("Yes! Yes!") as the Prime Minister read it. The two men signed the paper then and there. When, later that day, German Foreign Minister Joachim von Ribbentrop remonstrated with Hitler for signing it, the Führer replied, "Oh, don't take it so seriously. That piece of paper is of no further significance whatever." Chamberlain, on the other hand, when he returned to his hotel for lunch, patted his breast pocket and said, "I've got it!" Word leaked as to the outcome of the meetings before Chamberlain's return, causing delight among many in London, though gloom amongst Churchill and his adherents.

Chamberlain returned to London in triumph. Large crowds mobbed Heston, where he was met by the Lord Chamberlain, the Earl of Clarendon, who gave him a letter from King George VI, assuring him of the Empire's lasting gratitude and urging him to come straight to Buckingham Palace to report. The streets were so packed with cheering people that it took Chamberlain an hour and a half to journey the nine miles from Heston to the Palace. After reporting to the King, Chamberlain and his wife appeared on the Palace balcony with the King and his wife, Queen Elizabeth. He then went to Downing Street, where both the street and the front hall of Number 10 were packed. As he headed upstairs to address the crowd from a first floor window, someone called to him, "Neville, go up to the window and say 'peace in our time'." Chamberlain turned around and responded, "No, I don't do that sort of thing." Nevertheless, Chamberlain recalled the words of his predecessor, Benjamin Disraeli and his return from the Congress of Berlin in his statement to the crowd:

My good friends, this is the second time there has come back from Germany to Downing Street peace with honour. I believe it is peace for our time. We thank you from the bottom of our hearts. Now I recommend you go home, and sleep quietly in your beds.

King George issued a statement to his people, "After the magnificent efforts of the Prime Minister in the cause of peace, it is my fervent hope that a new era of friendship and prosperity may be dawning among the peoples of the world." When the King met with Duff Cooper, who resigned as First Lord over the Munich Agreement, he told Cooper that he respected people who had the courage of their convictions, but could not agree with him. He wrote to his mother, Queen Mary, that "the Prime Minister was delighted with the results of his mission, as are we all". The dowager queen responded to her son with anger against those who spoke against the Prime Minister: "He brought home peace, why can't they be grateful?" Most newspapers supported Chamberlain uncritically, and he received thousands of gifts, from a silver dinner service to many of his trademark umbrellas. The Commons discussed the Munich Agreement on 3 October; though Cooper opened by setting forth the reasons for his resignation and Churchill spoke harshly against the pact, no Conservative voted against the government, and only between 20 and 30 abstained, including Churchill, Eden, Cooper and Harold Macmillan. Churchill told the Commons, "England has been offered a choice between war and shame. She has chosen shame, and will get war."

In the aftermath of Munich, Chamberlain pursued a course of cautious rearmament. He told the Cabinet in early October, "[I]t would be madness for the country to stop rearming until we were convinced that other countries would act in the same way. For the time being, therefore, we should relax no particle of effort until our deficiencies had been made good." However, later in October, he resisted calls to put industry on a war footing, convinced that such an action would show Hitler that the Prime Minister had decided to abandon Munich. Chamberlain hoped that the understanding he had signed with Hitler at Munich would lead towards a general settlement of European disputes; however, Hitler expressed no public interest in following up on the accord. Having considered a general election immediately following Munich, Chamberlain instead reshuffled his Cabinet. By the end of the year, however, public concerns caused Chamberlain to conclude that "to get rid of this uneasy and disgruntled House of Commons by a General Election" would be "suicidal".

Despite Hitler's relative quietness as the Reich absorbed the Sudetenland, foreign policy concerns continued to preoccupy Chamberlain. He made trips to Paris and Rome, hoping to persuade the French to hasten their rearmament, and to persuade Mussolini to be a positive influence on Hitler. However, several of his Cabinet members, led by the Foreign Secretary Lord Halifax, began to draw away from the appeasement policy. Halifax was now convinced that Munich, though "better than a European war", had been "a horrid business and humiliating". Public revulsion over the pogrom of Kristallnacht on 9 November made any attempt at a rapprochement with Hitler unacceptable, though Chamberlain did not abandon his hopes.

Still hoping for reconciliation with Germany, Chamberlain made a major speech at Birmingham on 28 January in which he expressed his desire for international peace, and had an advance copy sent to Hitler at Berchtesgaden. Hitler seemed to respond; in his Reichstag speech on 30 January, he stated that he wanted a "long peace". Chamberlain was confident that improvements in British defence since Munich would bring the dictator to the bargaining table. This belief was reinforced by a German official's conciliatory speech welcoming Ambassador Henderson back to Berlin after an absence for medical treatment in Britain. Chamberlain responded with a speech in Blackburn on 22 February, hoping that the nations would resolve their differences through trade, and was gratified when his comments were printed in German newspapers. With matters appearing to improve, Chamberlain's rule over the House of Commons was firm, and he was convinced the government would "romp home" in a late 1939 election.

On 15 March, Germany invaded the Czech provinces of Bohemia and Moravia, including Prague. Though Chamberlain's initial parliamentary response was, according to biographer Nick Smart, "feeble", within 48 hours he had spoken more forcefully against the German aggression. In the 17 March speech, given at Birmingham, he warned that "no greater mistake could be made than to suppose that because it believes war to be a senseless and cruel thing, the nation has so lost its fibre that it will not take part to the utmost of its power in resisting such a challenge if it were ever made". The Prime Minister questioned whether the invasion of Czechoslovakia was "the end of an old adventure, or the beginning of a new" and whether it was "a step in the direction of an attempt to dominate the world by force". The Colonial Secretary, Malcolm MacDonald stated, "whereas the Prime Minister was once a strong advocate of peace, he has now definitely swung around to the war point of view". This speech was met with widespread approval in Britain and recruitment for the armed services increased considerably.

Chamberlain sought to build an interlocking series of defence pacts among the remaining European countries as a means of deterring Hitler from war. He sought an agreement among Britain, France, the USSR and Poland whereby the first three would go to the assistance of Poland if her independence were threatened, but Polish mistrust of the Soviet Union caused those negotiations to fail. Instead, on 31 March, Chamberlain informed an approving House of Commons of British and French guarantees that they would lend Poland all possible aid in the event of any action which threatened Polish independence. In the ensuing debate, Eden stated that the nation was now united behind the government. Even Churchill and Lloyd George praised Chamberlain's government for issuing the guarantee to Poland.

The Prime Minister took other steps to deter Hitler from aggression. He doubled the size of the Territorial Army, created a Ministry of Supply to expedite the provision of equipment to the armed forces, and instituted peacetime conscription. The Italian invasion of Albania on 7 April led to guarantees being given to Greece and Romania.

Chamberlain was reluctant to seek military alliance with the Soviet Union, distrusting Joseph Stalin ideologically and feeling that there was little to gain given the massive purges that recently had taken place in the Red Army. However, much of his Cabinet favoured such an alliance, and when Poland withdrew her objection to Anglo – Soviet alliance, Chamberlain had little choice but to proceed. The talks with Soviet Foreign Minister Vyacheslav Molotov, to which Britain sent only a low-level delegation, dragged on over several months, and eventually foundered on 14 August when Poland and Romania refused to allow Soviet troops to be stationed on their territories. A week after the failure of these talks, the Soviet Union and Germany signed the Molotov - Ribbentrop Pact, which committed the countries to non-aggression towards each other. A secret annexe of the agreement divided up Poland in the event of war. Chamberlain had disregarded rumours of a Soviet - German rapprochement, and was dismissive of the publicly announced pact, stating that it in no way affected British obligations towards Poland. Nevertheless, on 23 August, he had Henderson deliver a letter to Hitler telling him that Britain was fully prepared to live up to its obligations to Poland. Hitler instructed his generals to prepare for an invasion of Poland, telling them, "Our enemies are small worms. I saw them at Munich."

Germany invaded Poland in the early morning hours of 1 September 1939. The British Cabinet met late that morning and issued a warning to Germany that unless it withdrew from Polish territory, Britain would carry out its obligations to Poland. When the Commons met at 6:00 p.m., Chamberlain and Labour deputy leader Arthur Greenwood (deputising for the sick Clement Attlee) entered the chamber to loud cheers. Chamberlain spoke emotionally, laying the blame for the war on Hitler.

No formal declaration of war was immediately made. French Foreign Minister Georges Bonnet stated that France could do nothing until its parliament met on the evening of 2 September. In fact, Bonnet was trying to rally support for a Munich style summit proposed by the Italians to be held on 5 September. The British Cabinet, however, demanded that Hitler be given an ultimatum at once, and if troops were not withdrawn by the end of 2 September, that war be declared forthwith. Chamberlain and Halifax were convinced by Bonnet's pleas from Paris that France needed more time for mobilisation and evacuation, and postponed the expiration of the ultimatum (which had in fact not yet been served). The Commons received Chamberlain's lengthy statement, which made no mention of an ultimatum, badly, and when Greenwood rose to "speak for the working classes", Conservative backbencher Leo Amery urged him to "Speak for England, Arthur", implying that the Prime Minister was not so speaking. Chamberlain replied that telephone difficulties were making it hard to communicate with Paris, and tried to dispel fears that the French were weakening. He had little success; too many members knew of Bonnet's efforts. National Labour MP and diarist Harold Nicolson later wrote, "In those few minutes, he flung away his reputation." The seeming delay gave rise to fears Chamberlain would again seek a settlement with Hitler. Chamberlain's last peacetime Cabinet met at 11:30 that night, with a thunderstorm raging outside, and determined that the ultimatum would be presented in Berlin at nine o'clock the following morning, to expire two hours later, prior to the Commons convening at noon. At 11:15 a.m., Chamberlain addressed the nation by radio, telling it that it was now at war with Germany:

We have a clear conscience, we have done all that any country could do to establish peace. The situation in which no word given by Germany's ruler could be trusted, and no people or country could feel itself safe had become intolerable ... Now may God bless you all. May He defend the right. It is the evil things we shall be fighting against — brute force, bad faith, injustice, oppression, and persecution — and against them I am certain that the right will prevail.

That afternoon, Chamberlain addressed the Commons's first Sunday session in over 120 years. He spoke to a quiet House in a statement which even opponents termed "restrained and therefore effective":

Everything that I have worked for, everything that I have hoped for, everything that I have believed in during my public life has crashed into ruins. There is only one thing left for me to do: that is devote what strength and power I have to forwarding the victory of the cause for which we have sacrificed so much.

Chamberlain instituted a War Cabinet, and invited the Labour and Liberal parties to join his government, which they declined. He restored Churchill to the Cabinet as First Lord of the Admiralty with a seat in the War Cabinet. Chamberlain also gave Eden a government post. The new First Lord proved to be a difficult Cabinet colleague, deluging the Prime Minister with a sea of lengthy memos. Chamberlain castigated Churchill for sending so many memos as unnecessary when the two met in War Cabinet every day. Chamberlain suspected, correctly as it proved after the war, that "these letters are for the purpose of quotation in the Book that he will write hereafter". Chamberlain was also able to deter some of Churchill's more extreme plans, such as Operation Catherine, which would have sent several heavily armoured ships into the Baltic Sea with little support and no air cover as a means of stopping shipments of iron ore to Germany. With the naval war the only significant front involving the British in the early months of the war, the First Lord's obvious desire to wage a ruthless, victorious war established him as a leader-in-waiting in the public consciousness and among parliamentary colleagues.

With little land action in the west, the initial months of the war were dubbed the "Bore War", later renamed the "Phoney War" by journalists. Chamberlain, in common with most Allied officials and generals, felt the war could be won relatively quickly by keeping economic pressure on Germany through a blockade, while continuing rearmament. Chamberlain was reluctant to go too far in altering the British economy. The government submitted an emergency war budget about which Chamberlain stated, "the only thing that matters is to win the war, though we may go bankrupt in the process". However, actual government expenditures rose by little more than the rate of inflation between September 1939 and March 1940. Despite these difficulties, Chamberlain still enjoyed approval ratings as high as 68% and almost 60% in April 1940.

In early 1940, the Allies approved a campaign to take control of northern Norway, including the key port of Narvik, and possibly also to seize the iron mines at Gällivare in northern Sweden, from which Germany obtained much of its iron ore. Since the Baltic froze in winter, the iron ore was sent by ship south from Narvik during part of the year. The Allies planned to begin by mining Norwegian waters, provoke a German reaction in Norway, and proceed to occupy much of the country. Unforeseen by the Allies, however, Germany had itself planned to occupy Norway, and on 9 April German troops occupied Denmark and began an invasion of Norway. German troops quickly occupied much of the country. The Allies sent troops to Norway, who met with little success, and on 26 April, the War Cabinet ordered a withdrawal. The Prime Minister's opponents decided to turn the adjournment debate for the Whitsun recess into a challenge to Chamberlain, who soon heard about the plan. After initial anger, Chamberlain determined to fight.

What became known as the "Norway debate" opened on 7 May, and lasted for two days. The initial speeches, including Chamberlain's, were nondescript, but Admiral Sir Roger Keyes, member for Portsmouth North, in full uniform, delivered a withering attack on the conduct of the Norway campaign, though he excluded Churchill from criticism. Leo Amery then delivered a speech which he concluded by echoing Oliver Cromwell's words on dissolving the Long Parliament: "You have sat here too long for any good you are doing. Depart, I say, and let us have done with you. In the name of God, go!" When Labour announced that they would call for a division of the House, Chamberlain called upon his "friends — and I still have some friends in this House — to support the Government tonight". Though the use of the word "friends" was a conventional term to refer to party colleagues, and, according to biographer Robert Self, many MPs took it that way, it was an "error of judgment" for Chamberlain to refer to party loyalty "when the gravity of the war situation required national unity". Lloyd George joined the attackers and Churchill concluded the debate with a vigorous speech in support of the government. When the division took place, the government, which had a normal majority of over 200, prevailed by only 81, with 38 MPs in receipt of the government whip voting against it, and between 20 and 25 abstaining.

Chamberlain spent much of 9 May in meetings with his Cabinet colleagues. Many Conservative MPs, even those who had voted against the government, indicated on 9 May and in the days following that they did not wish Chamberlain to depart, but rather to reconstruct his government. However, he decided that he would resign unless the Labour Party was willing to join his government, and met with Attlee later that day. Attlee was unwilling, but did agree to consult his National Executive, then meeting in Bournemouth. Chamberlain favoured Halifax as the next Prime Minister, but Halifax proved reluctant to press his own claims, and Churchill emerged as the choice. The following day, Germany invaded the Low Countries, and Chamberlain considered remaining in office. However, Attlee confirmed that Labour would not serve under Chamberlain, though it was willing to serve under someone else, and Chamberlain went to Buckingham Palace to resign and advise the King to send for Churchill. Churchill later expressed gratitude to Chamberlain for not advising the King to send for Halifax, who would have commanded the support of most government MPs. In a resignation broadcast that evening, Chamberlain told the nation,

For the hour has now come when we are to be put to the test, as the innocent people of Holland, Belgium, and France are being tested already. And you, and I, must rally behind our new leader, and with our united strength, and with unshakable courage fight and work until this wild beast, which has sprung out of his lair upon us, has been finally disarmed and overthrown.

Queen Elizabeth told Chamberlain that her daughter, Princess Elizabeth, wept as she heard the broadcast. Churchill wrote to express his gratitude for Chamberlain's willingness to stand by him in the nation's hour of need, and Lord Baldwin, the only living former Prime Minister besides Chamberlain and Lloyd George, wrote, "You have passed through fire since we were talking together only a fortnight ago, and you have come out pure gold."

In a departure from usual practice, Chamberlain did not issue any resignation Honours list. With Chamberlain remaining leader of the Conservative Party, and with many MPs still supporting him and distrusting the new Prime Minister, Churchill refrained from any purge of Chamberlain loyalists. Churchill wished Chamberlain to return to the Exchequer, which he declined, convinced that accepting would lead to difficulties with the Labour Party. Instead, he accepted the post of Lord President of the Council with a seat in the shrunken five-member War Cabinet. When Chamberlain entered the House of Commons on 13 May 1940, for the first time since his resignation, "MPs lost their heads, they shouted, they cheered, they waved their order papers, and his reception was a regular ovation." However, Churchill was received coolly by the House. Some of Churchill's great speeches to the House, such as "We shall fight on the beaches", met with only half-hearted enthusiasm there.

His fall from power left Chamberlain deeply depressed, writing, "Few men can have known such a reversal of fortune in so short a time." He especially regretted the loss of Chequers as "a place where I have been so happy", though after a farewell visit there by the Chamberlains on 19 June, he wrote "I am content now that I have done that, and shall put Chequers out of my mind." As Lord President he assumed vast responsibilities over domestic issues and chaired the War Cabinet during Churchill's many absences. Attlee later remembered him as "free from any of the rancour he might have felt against us. He worked very hard and well: a good chairman, a good committeeman, always very businesslike". As chairman of the Lord President's Committee, he exerted great influence over the wartime economy. When Axis feelers for peace reached the War Cabinet on 26 May 1940, with the Benelux nations conquered and France tottering, Halifax urged following up and seeing if the actual offer was worthwhile. The battle over the course of action within the War Cabinet lasted three days, and Chamberlain's statement on the final day that there was unlikely to be an acceptable offer and that the feelers should not be pursued at that time helped persuade the War Cabinet to reject negotiations.

Twice in May 1940, Churchill broached the subject of bringing Lloyd George into the government. Each time, Chamberlain indicated that due to their longtime antipathy, he would immediately retire if Lloyd George was appointed a minister. Churchill did not appoint Lloyd George, but brought up the subject with Chamberlain again early in June. This time, Chamberlain agreed to Lloyd George's appointment provided Lloyd George gave a personal assurance to put aside the feud. However, Lloyd George refused to serve in Churchill's government.

Chamberlain worked to bring his Conservative Party in line behind Churchill, working with the Chief Whip, David Margesson, to overcome members' suspicion and dislike of the Prime Minister. On 4 July, Churchill entered the Chamber to a great cheer from Conservative MPs orchestrated by the two, and the Prime Minister was almost overcome with emotion at the first cheer he had received from his own party's benches since May. Churchill returned the loyalty, refusing to consider Labour and Liberal attempts to expel Chamberlain from the government. When criticisms of Chamberlain appeared in the press, and when the former Prime Minister learned that Labour intended to use an upcoming secret session of Parliament as a platform to attack him, Chamberlain told Churchill that he could only defend himself by attacking Labour. The Prime Minister intervened with the Labour Party and the press, and the criticism ceased, according to Chamberlain, "like turning off a tap".

In July 1940, a polemic entitled Guilty Men was released by "Cato" — a pseudonym for three journalists (including future Labour leader Michael Foot) from the Beaverbrook publishing stable. The piece attacked the record of the National Government, alleging that it had failed to prepare adequately for war. It called for the removal of Chamberlain and other ministers who had allegedly contributed to the British disasters of the early part of the war. The short book sold more than 200,000 copies, many of which were passed from hand to hand, and went into twenty-seven editions in the first few months despite not being carried by several major bookshops. According to historian David Dutton, "its impact upon Chamberlain's reputation, both among the general public and within the academic world, was profound indeed".

Chamberlain had long enjoyed excellent health, except for occasional attacks of gout, but by July 1940, he was in almost constant pain. He sought treatment, and later that month entered hospital for surgery. Surgeons discovered that he was suffering from terminal bowel cancer, but they concealed it from him, telling him that he would not require further surgery. Chamberlain left the nursing home where he was staying for Highfield Park in Hampshire, and resumed work in mid-August. He returned to his office on 9 September. However, renewed pain, compounded by the night-time bombing of London, which forced him to go to an air raid shelter and denied him rest, sapped his energy, and he left London for the last time on 19 September, returning to Highfield Park. He proffered his resignation to Churchill on 22 September, which the Prime Minister was initially reluctant to accept. However, as both men realised that Chamberlain would never return to work, Churchill finally allowed him to resign. The Prime Minister asked if Chamberlain would accept the highest order of British chivalry, the Order of the Garter, of which his brother had been a member. Chamberlain refused, stating that he would "prefer to die plain 'Mr. Chamberlain' like my father before me, unadorned by any title".

In the short time remaining to him, Chamberlain was angered by the "short, cold & for the most part depreciatory" press comments on his retirement, according to him written "without the slightest sign of sympathy for the man or even any comprehension that there may be a human tragedy in the background". However, the King and Queen drove down from Windsor to visit the dying man on 14 October. He received hundreds of sympathetic letters from friends and supporters. He wrote to John Simon, who had served as Chancellor of the Exchequer in Chamberlain's government:

[I]t was the hope of doing something to improve the conditions of life for the poorer people that brought me at past middle life into politics, and it is some satisfaction to me that I was able to carry out some part of my ambition, even though its permanency may be challenged by the destruction of war. For the rest I regret nothing that I have done & I can see nothing undone that I ought to have done. I am therefore content to accept the fate that has so suddenly overtaken me.

Chamberlain died of bowel cancer on 9 November 1940 at the age of 71. His funeral service took place at Westminster Abbey (due to wartime security concerns, the date and time were not widely publicised), and his ashes were interred there next to those of Andrew Bonar Law. Churchill eulogised Chamberlain in the House of Commons, three days after his death:

Whatever else history may or may not say about these terrible, tremendous years, we can be sure that Neville Chamberlain acted with perfect sincerity according to his lights and strove to the utmost of his capacity and authority, which were powerful, to save the world from the awful, devastating struggle in which we are now engaged. This alone will stand him in good stead as far as what is called the verdict of history is concerned.

Though some Chamberlain supporters found Churchill's oratory to be faint praise of the late Prime Minister, Churchill added less publicly, "Whatever shall I do without poor Neville? I was relying on him to look after the Home Front for me." Amongst the others who paid tribute to Chamberlain in the Commons and in the House of Lords on 12 November were Lord Halifax, Attlee, and the Liberal Party leader and Air Minister, Sir Archibald Sinclair. Lloyd George, the only former Prime Minister remaining in the Commons, had been expected to speak, but absented himself from the proceedings.

A few days before his death, Neville Chamberlain wrote,

So far as my personal reputation is concerned, I am not in the least disturbed about it. The letters which I am still receiving in such vast quantities so unanimously dwell on the same point, namely without Munich the war would have been lost and the Empire destroyed in 1938 ... I do not feel the opposite view ... has a chance of survival. Even if nothing further were to be published giving the true inside story of the past two years, I should not fear the historian's verdict.

Guilty Men was not the only Second World War tract that damaged Chamberlain's reputation. We Were Not All Wrong, published in 1941, took a similar tack as Guilty Men, arguing that Liberal and Labour MPs, and a small number of Conservatives, had fought against Chamberlain's appeasement policies. The author, Liberal MP Geoffrey Mander, had voted against conscription in 1939. Another polemic against Conservative policies was Why Not Trust the Tories (1944, written by "Gracchus", who later proved to be future Labour minister Aneurin Bevan), which castigated the Conservatives for the foreign policy decisions of Baldwin and Chamberlain. Though a few Conservatives offered their own versions of events, most notably MP Quintin Hogg in his 1945 The Left was Never Right, by the end of the war, there was a very strong public belief that Chamberlain was culpable for serious diplomatic and military misjudgments that had nearly caused Britain's defeat.

Chamberlain's reputation was devastated by these attacks from the left. In 1948, with the publication of The Gathering Storm, the first volume of Churchill's six-volume set, The Second World War, Chamberlain sustained an even more serious assault from the right. While Churchill stated privately, "this is not history, this is my case", his series was still hugely influential. Churchill depicted Chamberlain as well-meaning but weak, blind to the threat posed by Hitler, and oblivious to the fact that (according to Churchill) Hitler could have been removed from power by a grand coalition of European states. Churchill suggested that the year's delay between Munich and war worsened Britain's position, and criticised Chamberlain for both peacetime and wartime decisions. In the years following the publication of Churchill's books, few historians questioned his judgment.

Anne Chamberlain, the former premier's widow, suggested that Churchill's work was filled with matters that "are not real misstatements that could easily be corrected, but wholesale omissions and assumptions that certain things are now recognised as facts which actually have no such position". During the war, the Chamberlain family had commissioned historian Keith Feiling to produce an official biography, and gave him access to Chamberlain's private diaries and papers. While Feiling had the right of access to official papers as the official biographer of a recently deceased person, he may not have been aware of the provision, and the Cabinet Secretary denied his requests for access. Though Feiling produced what historian David Dutton described in 2001 as "the most impressive and persuasive single-volume biography" of Chamberlain (completed during the war and published in 1946), he could not repair the damage already done to Chamberlain's reputation.

Conservative MP Iain Macleod's 1961 biography of Chamberlain was the first major biography of a revisionist school of thought on Chamberlain. The same year, A.J.P. Taylor, in his The Origins of the Second World War, found that Chamberlain had adequately rearmed Britain for defence (though a rearmament designed to defeat Germany would have taken massive additional resources) and described Munich as "a triumph for all that was best and most enlightened in British life  ... [and] for those who had courageously denounced the harshness and short sightedness of Versailles".

The adoption of the Thirty Year Rule in 1967 made available many of the papers of the Chamberlain government over the subsequent three years, helping to explain why Chamberlain acted as he did. The resultant works greatly fuelled the revisionist school, although they also included books that strongly criticised Chamberlain, such as Keith Middlemas's 1972 Diplomacy of Illusion (which portrayed Chamberlain as a seasoned politician with strategic blindness when it came to Germany). Released papers indicated that, contrary to claims made in Guilty Men, Chamberlain had neither ignored the advice of the Foreign Office, nor had he disregarded and run roughshod over his Cabinet. Other released papers showed that Chamberlain had considered seeking a grand coalition amongst European governments, like that later advocated by Churchill, and had rejected it on the ground that the division of Europe into two camps would make war more, not less likely. They also showed that Chamberlain had been advised that the Dominions, pursuing independent foreign policies under the Statute of Westminster, had indicated that Chamberlain could not depend on their help in the event of a Continental war. The Chiefs of Staff report, which indicated that Britain could not forcibly prevent Germany from conquering Czechoslovakia, was first publicly known at this time.

In reaction against the revisionist school of thought regarding Chamberlain, a post-revisionist school emerged, beginning in the 1990s, using the released papers to justify the initial conclusions of Guilty Men. Oxford historian R.A.C. Parker argued that Chamberlain could have forged a close alliance with France after the Anschluss, in early 1938, and begun a policy of containment of Germany under the auspices of the League of Nations. While many revisionist writers had suggested that Chamberlain had had few or no choices in his actions, Parker argued that Chamberlain and his colleagues had chosen appeasement over other, viable policies. In his two volumes, Chamberlain and Appeasement (1993) and Churchill and Appeasement (2000), Parker stated that Chamberlain, due to his "powerful, obstinate personality" and his skill in debate, caused Britain to embrace appeasement instead of effective deterrence. Parker also suggested that had Churchill held high office in the second half of the 1930s, he would have built a series of alliances which would have deterred Hitler, and perhaps would have caused Hitler's domestic opponents to procure his removal.

Dutton observes that Chamberlain's reputation, for good or ill, will probably always be closely tied to evaluation of his policy towards Germany:

Whatever else may be said of Chamberlain's public life his reputation will in the last resort depend upon assessments of this moment [Munich] and this policy [appeasement]. This was the case when he left office in 1940 and it remains so sixty years later. To expect otherwise is rather like hoping that Pontius Pilate will one day be judged as a successful provincial administrator of the Roman Empire.