Ernest Augustus I (5 June 1771 – 18 November 1851) was King of Hanover from 20 June 1837 until his death. He was the fifth son and eighth child of George III, who reigned in both the United Kingdom and Hanover. As a fifth son, initially Ernest seemed unlikely to become a monarch, but Salic Law, which barred women from the succession, applied in Hanover and none of his older brothers had legitimate male issue.

Ernest was born in England, but was sent to Hanover in his adolescence for his education and military training. While serving with Hanoverian forces in Wallonia against Revolutionary France, he received a disfiguring facial wound. In 1799, he was created Duke of Cumberland and Teviotdale. Although his 1815 marriage to the twice widowed Frederica of Mecklenburg - Strelitz met with the disapproval of his mother, Queen Charlotte, it proved a happy relationship. By 1817, the mad King George III had only one legitimate grandchild, Princess Charlotte of Wales, and when she died in childbirth, Ernest was the senior son to be both married and not estranged from his wife. This gave him some prospect of succeeding to the British throne. However, both of his unmarried older brothers quickly married, and King George's fourth son, Edward, Duke of Kent, fathered the eventual British heir, Princess Victoria of Kent. Ernest was active in the House of Lords, where he maintained an extremely conservative record. There were persistent allegations (reportedly spread by his political foes) that he had murdered his valet and had fathered a son by his sister, Princess Sophia of the United Kingdom. Before Victoria succeeded to the British Throne, it was rumoured that Ernest intended to murder her and take the Throne himself. When King William IV died on 20 June 1837, Ernest ascended the Hanoverian Throne. Hanover's first ruler to reside in the kingdom since George I, he had a generally successful fourteen year reign, but excited controversy when he dismissed the Göttingen Seven (including the two Brothers Grimm) from their professorial positions for agitating against his policies.

Ernest Augustus, the fifth son of George III and Queen Charlotte, was born at Buckingham House, now part of Buckingham Palace, on 5 June 1771. After leaving the nursery, he lived with his two younger brothers, Prince Adolphus (later Duke of Cambridge) and Prince Augustus (later Duke of Sussex), and a tutor in a house on Kew Green, near his parents' residence at Kew Palace. At the age of fifteen, he and his two younger brothers were sent to the University of Göttingen, located in his father's domain of Hanover. Though the King never left the United Kingdom in his life, he sent his younger sons to Germany in their adolescence. According to historian John Van der Kiste, this was done to limit the influence Ernest's eldest brother George, Prince of Wales, who was leading an extravagant lifestyle, would have over his younger brothers. Prince Ernest proved an apt student, and after being tutored privately for a year, while learning German, attended lectures at the University. Though King George ordered that the princes' household be run along military lines, and that they follow university rules, the town merchants proved willing to extend credit to the princes, and all three fell into debt.

In 1790, Ernest asked his father for permission to train with Prussian forces. Instead, in January 1791, he and Prince Adolphus were sent to Hanover to receive military training under the supervision of Field Marshal Wilhelm von Freytag. Before leaving Göttingen, Ernest penned a formal letter of thanks to the university, and wrote to his father, "I should be one of the most ungrateful of men if ever I was forgetful of all I owe to Göttingen & its professors."

Ernest learned cavalry drill and tactics under Captain von Linsinger of the Queen's Light Dragoons, and proved to be an excellent horseman as well as a good shot. After only two months of training, von Freytag was so impressed by the Prince's progress that he gave him a place in the cavalry as captain. Ernest was supposed to receive infantry training, but the King, also impressed by his son's prowess, allowed him to remain with the cavalry.

In March 1792, the King commissioned Prince Ernest Augustus as a colonel in the 9th Hanoverian Light Dragoons. The Prince served in the Low Countries in the War of the First Coalition, under his elder brother Frederick, Duke of York, then commander of the combined British, Hanoverian and Austrian forces. Seeing action near the Walloon town of Tournai in August 1793, he sustained a sabre wound to the head, which resulted in a disfiguring scar. During the Battle of Tourcoing in northern France on 18 May 1794 his left arm was injured by a cannonball which passed close by him. In the days after the battle, the sight in his left eye faded. In June, he was sent to Britain to convalesce, his first stay there since 1786.

Ernest resumed his duties in early November, by now promoted to major - general. He hoped his new rank would bring him a corps or brigade command, but none was forthcoming as Allied armies retreated slowly through the Netherlands towards Germany. By February 1795, they had reached Hanover. Ernest remained in Hanover over the next year, at several unimportant postings. He had requested a return home to seek treatment for his eye, but it was not until early 1796 that the King agreed and allowed Ernest to return to Britain. In Britain, Prince Ernest consulted the noted eye doctor, Wathen Waller, but Waller apparently found the condition inoperable, as no operation took place. Once in Britain, Ernest repeatedly sought to be allowed to join British forces on the Continent, even threatening to join the Yeomanry as a private, but both the King and the Duke of York refused. Ernest did not want to rejoin Hanoverian forces, as the Hanoverians were not then involved in the fighting. In addition, von Freytag was seriously ill, and Ernest was unwilling to serve under his likely successor, General von Wallmoden.

On 23 April 1799, George III created Prince Ernest Augustus Duke of Cumberland and Teviotdale and Earl of Armagh. Though he was made a lieutenant - general, both of British and Hanoverian forces, he remained in England, and, with a seat in the House of Lords, entered politics. Ernest had extreme Tory views, and soon became a leader of the right of the party. King George had feared that Ernest, like some of his older brothers, would display Whig tendencies. Reassured on that point, in 1801, the King had Ernest conduct the negotiations which led to the formation of the Addington Government. In February 1802, King George granted his son the colonelcy of the 27th Light Dragoons, a post which offered the option of transfer to the colonelcy of the 15th Light Dragoons when a vacancy developed. A vacancy promptly occurred and the Duke became the colonel of the 15th Light Dragoons in March 1802. Although the post could have been a sinecure, Ernest involved himself in the affairs of the regiment and led it on manoeuvres.

In early 1803, the Duke of York appointed Ernest as commander of the Severn District, in charge of the forces in and around the Severn Estuary. When war with France broke out again after the Peace of Amiens, the elder Duke appointed Ernest to the more important Southwest District, comprising Hampshire, Dorset and Wiltshire. Though Ernest would have preferred command of the King's German Legion, composed mostly of expatriates from French occupied Hanover, he accepted the post. The Duke of Cumberland increased the defences on the South Coast, especially around the town of Weymouth, where his father often spent time in the summer.

The 1800 Acts of Union had given Ireland representation in Parliament, but existing law prevented the Irish Catholics from serving there because of their religion. "Catholic emancipation" was a major political issue of the first years of the 19th century. The Duke of Cumberland was a strong opponent of giving political rights to Catholics, believing that emancipation would be a violation of the King's Coronation Oath to uphold Anglicanism, and spoke out in the House of Lords against emancipation. Protestant Irish organisations supported the Duke; he was elected Chancellor of the University of Dublin in 1805 and Grand Master of the Orange Lodges two years later.

The Duke repeatedly sought a post with Allied forces fighting against France, but was sent to the Continent only as an observer. In 1807, he advocated sending British troops to join with the Prussians and Swedes and attack the French at Stralsund (today, in northeastern Germany). The Greville government refused to send forces. Shortly afterwards, the government fell, and the new Prime Minister, the Duke of Portland, agreed to send Ernest with 20,000 troops. However, they were sent too late: the French defeated Prussia and Sweden at the Battle of Stralsund before Ernest and his forces could reach the town.

In the early hours of 31 May 1810, Ernest, by his written account, was struck in the head several times while asleep in bed, awakening him. He ran for the door, where he was wounded in the leg by a sabre. He called for help, and one of his valets, Cornelius Neale, responded and aided him. Neale raised the alarm, and the household soon realised that Ernest's other valet, Joseph Sellis, was not among them, and that the door to Sellis's room was locked. The lock was forced, and Sellis was discovered with his throat freshly cut, a wound apparently self-inflicted. Ernest received several serious wounds during the apparent attack, and required over a month to recover from his injuries. The social reformer and anti-monarchist Francis Place managed to get on the inquest jury and became its foreman. Place went to the office of a barrister friend to study inquest law, and aggressively questioned witnesses. Place also insisted the inquest be opened to the public and press, and so cowed the coroner that he basically ran the inquest himself. Nevertheless, the jury returned a unanimous verdict of suicide against Sellis.

Much of the public blamed Ernest for Sellis's death. The more extreme Whig papers, anti-royal pamphleteers, and caricaturists all offered nefarious explanations for Sellis's death, in which the Duke was to blame. Some stories had the Duke cuckolding Sellis, with the attack as retaliation, or Sellis killed for finding Ernest and Mrs. Sellis in bed together. Others suggested that the Duke was the lover of either Sellis or Neale, and that blackmail had played a part in the death. Both Roger Fulford and John Van der Kiste, who wrote books about George III's children, ascribe part of the animus and fear towards the Duke to the fact that he did not conduct love affairs in public, as did his older brothers. According to them, the public feared what vices might be going on behind the locked doors of the Duke's house, and assumed the worst.

In early 1813, Ernest was involved in political scandal during an election contest in Weymouth following the general election the previous year. The Duke was shown to be one of three trustees who were able to dictate who would represent Weymouth in Parliament. It being considered improper for a peer to interfere in a Commons election, there was considerable controversy, and the Government sent Ernest to Europe as an observer to accompany Hanoverian troops, which were again engaged in war against France. Though he saw no action, Ernest was present at the Battle of Leipzig, a major victory for the Allies.

Ernest met and fell in love in mid 1813 with his first cousin, Frederica of Mecklenburg - Strelitz, wife of Frederick William, Prince of Solms - Braunfels and widow of Prince Louis of Prussia. The two agreed to wed if Frederica became free to marry. Her marriage to Frederick William had not been a success; her husband, seeing the marriage was beyond hope, agreed to a divorce, but his sudden death in 1814 removed the necessity. Some considered the death too convenient, and suspected the princess of poisoning her husband. Queen Charlotte opposed the marriage: before the princess had married Frederick William, she had jilted Ernest's brother, the Duke of Cambridge, after the engagement was announced.

Following the marriage in Germany on 29 May 1815, Queen Charlotte refused to receive her new daughter-in-law, nor would the Queen attend the resolemnisation of the Cumberlands' marriage at Kew, which Ernest's four older brothers attended. The Prince of Wales (now Prince Regent) found the Cumberlands' presence in Britain embarrassing, and offered him money and the Governorship of Hanover if they would leave for the Continent. Ernest refused, and the Cumberlands divided their time between Kew and St. James's Palace for the next three years. The Queen remained obstinate in her refusal to receive Frederica. Despite these family troubles, the Cumberlands had a happy marriage. The Government of Lord Liverpool asked Parliament to increase the Duke's allowance by ₤6,000 per year in 1815, so he could meet increased expenses due to his marriage. The Duke's involvement in the Weymouth election became an issue, and the bill failed by one vote. Liverpool tried again in 1817; this time the bill failed by seven votes.

At the time of the Duke's marriage in 1815, it seemed to have little dynastic significance to Britain. Princess Charlotte of Wales, only child of the Prince Regent, was the King's only legitimate grandchild. The young Princess was expected to have children who would secure the British succession, especially after she married Prince Leopold of Saxe - Coburg - Saalfeld in 1816. Both the Prince Regent and the Duke of York were married but estranged from their wives, while the next two brothers, the Dukes of Clarence and Kent, were unmarried. On 6 November 1817, Princess Charlotte died after delivering a stillborn son. King George was left with twelve surviving children, and no surviving legitimate grandchildren. Most of the unmarried royal dukes hurriedly sought out suitable brides and hastened to the altar, hoping to father the heir to the throne.

Seeing little prospect of the Queen giving in and receiving her daughter-in-law, the Cumberlands moved to Germany in 1818. They had difficulty living within their means in Britain, and the cost of living was much lower in Germany. Queen Charlotte died on 17 November 1818, but the Cumberlands remained in Germany, living principally in Berlin, where the Duchess had relatives. In 1817, the Duchess had a stillborn daughter; in 1819 she gave birth to a boy, Prince George of Cumberland. The Duke occasionally visited England, where he stayed with his eldest brother, who in 1820 succeeded to the British and Hanoverian Thrones as George IV. George III's fourth son, Edward, Duke of Kent, died six days before his father, but left a daughter, Princess Victoria of Kent. With the death of George III, Ernest became fourth in line to the British Throne, following the Duke of York (who would die without legitimate issue in 1827), the Duke of Clarence, and Princess Victoria.

In 1826, Parliament finally voted to increase Ernest's allowance. The Liverpool Government had argued that the Duke needed an increased allowance to pay for Prince George's education; even so, it was opposed by many Whigs. The bill, which passed the House of Commons 120–97, required Prince George to live in England if the Duke was to receive the money.

In 1828, Ernest was staying with the King at Windsor Castle when severe disturbances broke out in Ireland among Catholics. The Duke was an ardent supporter of the Protestant cause in Ireland, and returned to Berlin in August, believing that the Government, led by the Duke of Wellington, would deal firmly with the Irish. In January 1829, the Wellington Government announced that it would introduce a Catholic emancipation bill to conciliate the Irish. Disregarding a request from Wellington that he remain abroad, Ernest returned to London, and was one of the leaders against the Catholic Relief Act 1829, influencing King George against the bill. Within days of his arrival, the King instructed the officers of his Household to vote against the Bill. Hearing of this, Wellington told the King that he must resign as Prime Minister unless the King could assure him of complete support. The King initially accepted Wellington's resignation, and Ernest attempted to put together a government united against Catholic emancipation. Though such a government would have considerable support in the House of Lords, it would have little support in the Commons, and Ernest abandoned his attempt. The King recalled Wellington. The bill passed the Lords and became law.

The Wellington Government hoped that Ernest would return to Germany, but he moved his wife and son to Britain in 1829. The Times reported that they would live at Windsor in the "Devil's Tower"; instead, the Duke reopened his house at Kew. They settled there as rumours flew that Thomas Garth, thought to be the illegitimate son of Ernest's sister Princess Sophia, had been fathered by Ernest. It was also said that Ernest had blackmailed the King by threatening to expose this secret, though Van der Kiste points out that Ernest would have been ill-advised to blackmail with a secret which, if exposed, would destroy him. These rumours were spread as Ernest journeyed to London to fight against Catholic emancipation. Whig politician and diarist Thomas Creevey wrote about the Garth rumour in mid February, and there is some indication the rumours began with Princess Lieven, wife of the Russian ambassador.

Newspapers also reported, in July 1829, that the Duke had been thrown out of Lord Lyndhurst's house for assaulting his wife Sarah, Lady Lyndhurst. In early 1830, a number of newspapers printed articles hinting that Ernest was having an affair with Lady Graves, a mother of fifteen now past fifty. In February 1830, Lord Graves wrote a note to his wife expressing his confidence in her innocence, then cut his own throat. Two days after Lord Graves's death (and the day after the inquest), The Times printed an article connecting Lord Graves's death with Sellis's. After being shown the suicide note, The Times withdrew its implication there might be a connection between the two deaths. Nonetheless, many believed the Duke responsible for the suicide — or guilty of a second murder. The Duke later stated that he had been "accused of every crime in the decalogue". Ernest's biographer, Anthony Bird, states that while there is no proof, he has no doubt that the rumours against the Duke were spread by the Whigs for political ends. Another biographer, Geoffrey Willis, pointed out that no scandal had attached itself to the Duke during the period of over a decade when he resided in Germany; it was only when he announced his intent to return to Britain that "a campaign of unparalleled viciousness" began against him. According to Bird, Ernest was the most unpopular man in England.

The Duke's influence at Court was ended by the death of George IV in June 1830 and the succession of the Duke of Clarence as William IV. Wellington wrote that "The effect of the King's death will ... be to put an end to the Duke of Cumberland's political character and power in this country entirely". King William lacked legitimate children (two girls having died in infancy) and Ernest was now heir in Hanover, since the British heir, Victoria, as a female could not inherit there. William realized that so long as the Duke maintained a power base at Windsor, he could wield unwanted influence. The Duke was Gold Stick as head of the Household Cavalry; William made the Duke's post responsible to the Commander in Chief rather than to the King, and an insulted Ernest, outraged at the thought of having to report to an officer less senior than himself, resigned. King William again emerged triumphant when the new Queen, Adelaide of Saxe - Meiningen, wished to quarter her horses in the stables customarily used by the consort, but which were then occupied by Ernest's horses. Ernest initially refused the King's order to remove the horses, but gave in when told that William's grooms would remove them if Ernest did not move them voluntarily. However, Ernest and William remained friendly throughout the latter's seven-year reign. Ernest's house at Kew was too small for his family; the King gave the Duke and Duchess lifetime residence in a nearby, larger house by the entrance to Kew Gardens. Ernest opposed the Reform Act 1832, and was one of the "diehard" peers who voted against the bill on its final reading when most Tories abstained under threat of seeing the House of Lords flooded with Whig peers.

Ernest was the subject of more allegations in 1832, when two young women accused him of trying to ride them down as they walked near Hammersmith. The Duke had not left his grounds at Kew on the day in question, and was able to ascertain that the rider was one of his equerries, who professed not to have seen the women. Nevertheless, newspapers continued to print references to the incident, suggesting that Ernest had done what the women stated, and was cravenly trying to push blame on another. The same year, the Duke sued for libel after a book appeared accusing him of having his valet Neale kill Sellis, and the jury found against the author. Also in 1832, the Cumberlands suffered tragedy, as young Prince George went blind. The Prince had been blind in one eye from infancy; an accident at age thirteen took the sight of the other. Ernest had hoped his son might marry Princess Victoria and keep the British and Hanoverian Thrones united, but the handicap made it unlikely George could win Princess Victoria's hand, and raised questions about whether he should succeed in Hanover.

The Duke spent William's reign in the House of Lords, where he was assiduous in his attendance. Wrote newspaper editor James Grant, "He is literally — the door-keeper of course excepted — the first man in the House, and the last out of it. And this not merely generally, but every night." Grant, in his observations of the leading members of the House of Lords, indicated that the Duke was not noted for his oratory (he delivered no speech longer than five minutes) and had a voice that was difficult to understand, though, "his manner is most mild and conciliatory." Grant denigrated the Duke's intellect and influence, but stated that the Duke had indirect influence over several members, and that, "he is by no means so bad a tactician as his opponents suppose."

Controversy arose in 1836 over the Orange Lodges. The lodges (which took anti-Catholic views) were said to be ready to rise and try to put the Duke of Cumberland on the Throne on the death of King William. According to Joseph Hume, speaking in the House of Commons, Princess Victoria was to be passed over on the grounds of her age, sex, and incapacity. The Commons passed a resolution calling for the dissolution of the lodges. When the matter reached the Lords, the Duke defended himself, saying of Princess Victoria, "I would shed the last drop of my blood for my niece." The Duke indicated that the Orange Lodge members were loyal and were willing to dissolve the lodges in Great Britain. According to Bird, this incident was the source of the widespread rumours that the Duke intended to murder Princess Victoria and take the British Throne for himself.

On 20 June 1837, King William died, and Princess Victoria became Queen of the United Kingdom. Ernest became the King of Hanover. On 28 June 1837, King Ernest entered his new domain, passing under a triumphal arch. For the first time in over a century, Hanover would have a ruler living there. Many Hanoverians were of a liberal perspective, and would have preferred the popular viceroy, the Duke of Cambridge, to become king, but both of Ernest's younger brothers refused to lend themselves to any movement by which they would become king rather than their elder brother. According to Roger Fulford in his study of George III's younger sons, Royal Dukes, "In 1837, King Ernest was the only male descendant of George III who was willing and able to continue the connection with Hanover."

Hanover had received its first constitution, granted by the Prince Regent, in 1819; this did little more than denote Hanover's change from an electorate to a kingdom, granted by the Congress of Vienna. The Duke of Cambridge, as King William's viceroy in Hanover, recommended a thorough reorganisation of the Hanoverian government. William IV had given his consent to a new constitution in 1833; the Duke of Cumberland's consent was neither asked nor received, and he had formally protested against the constitution's adoption without his consent. One provision of the constitution transferred the Hanoverian Domains (the equivalent of the British Crown Estate) from the sovereign to the state, eroding the monarch's power.

Immediately upon his arrival in Hanover, the King dissolved the parliament which had been convened under the disputed constitution. On 5 July, he proclaimed the suspension of the constitution, on the ground that his consent had not been asked, and that it did not meet the kingdom's needs. On 1 November 1837, the King issued a patent, declaring the constitution void, but upholding all laws passed under it. The 1819 constitution was restored. The Crown Prince, Prince George, endorsed the action.

In carrying the King's patent into effect, the Cabinet required all officeholders (including professors at Göttingen University) to renew their oaths of allegiance to the King. Seven professors (including the two Brothers Grimm) refused to take the oaths, and agitated for others to protest against the King's decree. Since they did not take the oaths, the seven lost their positions, and the King expelled the three most responsible (including Jacob Grimm) from Hanover. Only one of the seven, orientalist Heinrich Ewald was a citizen of Hanover and he was not expelled. In the final years of the King's reign, the three were invited to return.

The King wrote of the incident to his brother-in-law, Frederick William III of Prussia, "If each of these seven gentlemen had addressed a letter to me expressing his opinion, I would have had no cause to take exception to their conduct. But to call a meeting and publish their opinions even before the Government had received their protest — that is what they have done and that I cannot allow." Ernest received a deputation of Göttingen citizens, who, fearing student unrest, applauded the dismissals. However, he was widely criticised in Europe, especially in Britain. In the House of Commons, MP Colonel Thomas Perronet Thompson proposed to Parliament that if the as-yet-childless Queen Victoria died, making Ernest the British King, Parliament should declare that King Ernest had forfeited all rights to the British Throne by his actions.

A more significant protest against the revocation of the 1833 constitution was the refusal of a number of towns to appoint parliamentary deputies. However, by 1840, a sufficient number of deputies had been appointed for the King to summon Parliament, which met for two weeks in August, approving a modified version of the 1819 constitution, passing a budget, and sending a vote of thanks to the King. The Parliament met again the following year, passed a three year budget, and adjourned again.

At the time the King took the throne, the city of Hanover was a densely packed residential town, and did not rise to the grand style of many German capitals. Once the political crises of the first years of his reign had subsided, he set out to remedy this state of affairs. Ernest's support led to gas lighting in the city streets of Hanover, up-to-date sanitation and the development of a new residential quarter. He had the plans altered in 1841, after Queen Frederica's death, to leave standing the Altes Palais, where the two had lived since arriving in Hanover. Ernest's interest in and support of the railroads led to Hanover becoming a major rail junction, much to the nation's benefit. However, when court architect Georg Ludwig Friedrich Laves in 1837 proposed the building of an opera house in Hanover, the King initially refused, calling the proposal "this utterly absurd idea of building a court theatre in the middle of this green field". The King finally gave his consent in 1844, and the opera house opened in 1852, a year after the King's death.

Every week, the King travelled with his secretary to different parts of his kingdom, and anyone could lay a petition before him — although Ernest had petitions screened by the secretary so he would not have to deal with frivolous complaints. Ernest opened high ministerial positions to those of any class, securing the services of several ministers who would not have been eligible without this reform. Though the King had, while Duke of Cumberland, fought against Catholic emancipation, he made no objection to Catholics in government service in Hanover, and even visited their churches. Ernest explained this by stating that there were no historical reasons to restrict Catholics in Hanover, as there had been in the United Kingdom. He continued to oppose admission of Jews into the British Parliament, but gave Jews in Hanover equal rights.

The King supported a postal union and common currency among the German states, but opposed the Prussian-led customs union, the Zollverein, fearing that it would lead to Prussian dominance and the end of Hanover as an independent state. Instead, the King supported the Steuerverein, which Hanover and other western German states had formed in 1834. When the Steuerverein treaties came up for renewal in 1841, Brunswick pulled out of the union and joined the Zollverein, greatly weakening Hanover's position, especially since Brunswick had enclaves within Hanover. Ernest was able to postpone the enclaves' entry into the Zollverein, and when a trade war began, was able to outlast Brunswick. In 1845, Brunswick, Hanover, and Prussia signed a trade agreement. In 1850, Ernest reluctantly permitted Hanover to join the Zollverein, though the entry was on favourable terms. Ernest's forebodings about Prussia were warranted; in 1866, fifteen years after his death, Hanover chose the Austrian side in the Austro - Prussian War, was defeated, and was annexed by Prussia.

Hanover was little affected by the revolutions of 1848; a few small disturbances were put down by the cavalry without bloodshed. When agitators arrived from Berlin at the end of May 1848, and there were demonstrations outside the King's palace, Ernest sent out the Prime Minister. The Prime Minister warned that if the demonstrators made any inappropriate demands on the King, Ernest would pack up his things and leave for Britain, taking the Crown Prince with him. This would leave the country to the mercy of expansionist Prussia, and the threat put an end to the agitation. Afterwards, the King granted a new constitution, somewhat more liberal than the 1819 document.

Ernest Augustus is supposed to have asked the advice of the Duke of Wellington as to what course he should take after Victoria's accession, with Wellington supposedly saying "Go before you are pelted out." However, Bird dismisses this story as unlikely, given Wellington's customary respect to royalty and the fact that Ernest had little choice in what to do — he had to repair to his kingdom as quickly as possible. One decision the new King did have to make was whether, in his capacity as Duke of Cumberland, to swear allegiance to Victoria in the House of Lords. Shortly after William's death, Ernest heard from Lord Lyndhurst that Lord Cottenham, the Lord Chancellor, had stated that he would refuse to administer the Oath of Allegiance to the King, as a foreign Sovereign. The King hurriedly appeared in the House of Lords, before his departure for Hanover, and subscribed to the Oath before the Chief Clerk as a matter of routine. Ernest was heir presumptive to his niece until the birth of Queen Victoria's daughter, also named Victoria, in November 1840. The Lord Privy Seal, Lord Clarendon, wrote, "What the country cares about is to have a life more, whether male or female, between the succession and the King of Hanover."

Almost immediately upon going to Hanover, the King became involved in a dispute with his niece. Victoria, who had a strained relationship with her mother, the Duchess of Kent, wanted to give the Duchess accommodation near her, for the sake of appearances — but not too near her. To that end, she asked the King to give up his apartments at St. James's Palace in favour of the Duchess. The King, wishing to retain apartments in London in anticipation of frequent visits to England, and reluctant to give way in favour of a woman who had frequently fought with his brother, King William, declined, and Victoria angrily rented a house for her mother. At a time when the young Queen was trying to pay off her father's debts, she saw this as unnecessary expense. Her ill-feeling towards the King increased when he refused, and advised his two surviving brothers to similarly refuse, to give precedence to her intended spouse, Albert of Saxe - Coburg and Gotha. Ernest argued that the standing of the various royal families had been settled at the Congress of Vienna, and the King of Hanover should not have to yield to one whom he described as a "paper Royal Highness". The act which naturalised Albert as a British subject left the question of his precedence unresolved.

Matters came to a head when Ernest returned for what would prove to be his only visit to England as King of Hanover, in 1843. He was welcomed warmly, everywhere but at the Palace. At the wedding of Princess Augusta of Cambridge, he attempted to insist on a superior place to that of Prince Albert. The 50-years-younger prince settled things with what Albert described as a "strong push", and carefully wrote his name on the certificate under the Queen's, so close to his wife's as to leave no space for the King's signature. The King apparently held no grudge, as he invited the Prince for a stroll in the park. When Albert demurred on the grounds that they might be jostled by crowds, the King replied, "When I lived here I was quite as unpopular as you are and they never bothered me."Shortly after the wedding, the King injured himself in a fall, with Albert writing to  his brother, "Happily he fell over some stones in Kew and damaged some ribs." This injury spared him further contact with Victoria and Albert. During his visit, the King found time to take his place as Duke of Cumberland in the House of Lords. Victoria recorded in her journal that the King had stated when asked if he would speak in the Lords, "No, I shall not, unless the Devil prompts me!" The Queen also recorded that though King Ernest greatly enjoyed listening to the debates, he did not himself speak.

The monarchs engaged in one more battle — over jewels left by Queen Charlotte. Victoria, who possessed them, took the position that they belonged to the British Crown. King Ernest maintained that they were to go to the heir male, that is, himself. The matter was arbitrated, and just as the arbitrators were about to announce a decision in Hanover's favour, one of the arbitrators died, voiding the decision. Despite the King's request for a new panel, Victoria refused to permit one during the King's lifetime, and took every opportunity to wear the jewels, causing the King to write to his friend, Lord Strangford, "The little Queen looked very fine, I hear, loaded down with my diamonds." The King's son and heir, King George V, pressed the matter, and in 1858, after another decision in Hanover's favour, the jewels were turned over to the Hanoverian ambassador.

The King made a point of welcoming British visitors, and when one Englishwoman told him that she had been lost in the city, the King denied that this was possible, as "the whole country is no larger than a fourpenny bit."

In 1851, the King undertook a number of journeys around Germany. He accepted an invitation from the Prussian Queen to visit Charlottenburg Palace, near Berlin. He visited Mecklenburg for the christening of the Grand Duke's son, and Lüneburg to inspect his old regiment. In June Ernest celebrated his 80th birthday by playing host to the King of Prussia. Late that summer, he visited Göttingen, where he opened a new hospital and was given a torchlight procession.

The King continued his interest in British affairs, and wrote to Lord Strangford about the Great Exhibition of 1851:

The folly and absurdity of the Queen in allowing this trumpery must strike every sensible and well-thinking mind, and I am astonished the ministers themselves do not insist on her at least going to Osborne during the Exhibition, as no human being can possibly answer for what may occur on the occasion. The idea ... must shock every honest and well meaning Englishman. But it seems everything is conspiring to lower us in the eyes of Europe.

The King died on 18 November 1851 after an illness of about a month. He was mourned greatly in Hanover; less so in England where The Times omitted the customary black border to its front page and claimed "the good that can be said of the Royal dead is little or none." Both he and Queen Frederica rest in a mausoleum in the Herrenhausen Gardens.

A large equestrian statue of King Ernest Augustus may be found in a square named after him in front of Hanover Central Station, inscribed with his name and the words (in German) "To the father of the nation from his loyal people." It is a popular meeting place; in the local phrase, people arrange to meet unterm Schwanz or "under the tail" (that is, of the horse which the King rides).

Although The Times denigrated Ernest's career as Duke of Cumberland, it did speak well of his time as King of Hanover, and of his success in keeping Hanover stable in 1848:

Above all, he possessed a resolute decision of character, which, however unfortunately it may have operated under different conditions, appeared to extraordinary advantage at the crisis of continental thrones. Bewildered by the revolutionary din, and oscillating ignominiously between fear and rage, resistance and concession, the clique of crowned heads suffered greatly by contrast with a Sovereign who at least knew his own mind, and was prepared to abide by his opinions. In the European convulsions, therefore, King Ernest maintained the stability of his throne and the tranquillity of his people without damage from revolution or reaction. As Kings, indeed, are computed on the continent, he was an able and even a popular Monarch, and his memory may find, perhaps, in his ancestral dominions a sympathy which it would be vain to bespeak for it in the scenes of his manhood or the land of his birth.