Keitel was born in Bad Gandersheim, Lower Saxony, Brunswick, German Empire, the son of Carl Keitel, a middle class landowner, and his wife Apollonia Vissering. After completing his education in Göttingen, he embarked on a military career in 1901, becoming a Fahnenjunker (Cadet Officer), joining the 6th Lower - Saxon Field Artillery Regiment. He married Lisa Fontaine, a wealthy landowner's daughter, in 1909. Together they had six children, one of whom died in infancy. His eldest son, Karl - Heinz Keitel went on to serve as a divisional commander in the Waffen-SS. During World War I Keitel served on the Western front with the Field Artillery Regiment No. 46. In September 1914, during the fighting in Flanders, he was severely wounded in his right forearm by a shell fragment.

Keitel recovered, and thereafter was posted to the German General Staff in early 1915. After World War I ended, he stayed in the newly created Reichswehr, and played a part in organizing Freikorps frontier guard units on the Polish border. Keitel also served as a divisional general staff officer, and later taught at the Hanover Cavalry School for two years.

In late 1924, Keitel was transferred to the Ministry of Defense (Reichswehrministerium), serving with the Troop Office (Truppenamt), the post - Versailles disguised General Staff. He was soon promoted to the head of the organizational department, a post he retained after the Nazi seizure of power in 1933. In 1935, based on a recommendation by Werner von Fritsch, Keitel was promoted to Lieutenant General and appointed as the departmental head of the Wehrmachtsamt (Armed Forces Office) which had the responsibility over all three branches of the armed forces.

In 1937, Keitel received a promotion to General. In the following year, after the Blomberg - Fritsch Affair, the Ministry of War (Reichskriegsministerium) was replaced by the Supreme Command of the Armed Forces (Oberkommando der Wehrmacht or OKW), and Keitel was appointed as its chief. This effectively made Keitel Germany's war minister, and accordingly he was appointed to the Cabinet. Soon after his appointment at OKW, he convinced Hitler to appoint his close friend, Walter von Brauchitsch, Commander - in - Chief of the Army.

For a brief period in October 1938, Keitel was Military Governor of the Sudetenland, but in February 1939 Keitel again became Chief of OKW; he retained that post until the end of the war.

During World War II, Keitel was one of the primary planners of the Wehrmacht campaigns and operations on the western and the eastern fronts. He advised Hitler against invading France and opposed Operation Barbarossa. Both times he backed down in the face of Hitler and tendered his resignation, which Hitler refused to accept.

In 1940, after the French campaign, he was promoted to Field Marshal along with several other generals. Unusual for a non-field commander, Keitel was awarded the Knight's Cross for arranging the armistice with France.

In 1942, he confronted Hitler in defense of Field Marshal Wilhelm List, whose Army Group A was stalled in the Battle of the Caucasus. Hitler spurned Keitel's pleading and fired List. Keitel's defense of List was his last act of defiance to Hitler; he never again challenged one of Hitler's orders. For example, during a strategy briefing late in the war, Luftwaffe intelligence discovered vast numbers of Soviet fighter aircraft ready to be deployed to the front. Reichsmarschall Hermann Göring, commander-in-chief of the Luftwaffe, told Hitler that they were simply dummies; the Red Air Force could not possibly have that many aircraft. Keitel then threw his hand to the table, and, although he knew the exact opposite was true, said "Mein Führer, the Reichsmarschall is correct."

Keitel unquestionably allowed Heinrich Himmler a free hand with his racial controls and ensuing terror in occupied Soviet territory. He also signed numerous orders of dubious legality under the laws of war. The most infamous were the Commissar Order (which stipulated that Soviet political commissars were to be shot on sight) and the Night and Fog Decree (which called for the forced disappearance of resistance fighters and other political prisoners in Germany's occupied territories). Another was the order that French pilots of the Normandie - Niemen squadron be executed rather than be made prisoners of war.

Keitel accepted Hitler's directive for Operation Citadel in 1943, despite strong opposition from several field officers who argued that neither the troops nor the new tanks on which Hitler staked his hopes for victory were ready.

Keitel played an important role in foiling the July 20 plot in 1944. Keitel then sat on the Army "Court of honour" that handed over many officers who were involved, including Field Marshal Erwin von Witzleben, to Roland Freisler's notorious People's Court.

In April and May 1945, during the Battle of Berlin, Keitel called for counterattacks to drive back the Soviet forces and relieve Berlin. However, there were insufficient German forces to carry out such attacks.

After Hitler's suicide on 30 April, Keitel stayed on as a member of the short lived Flensburg government under Grand Admiral Karl Dönitz.

On 8 May 1945, Dönitz authorized Keitel to sign an unconditional surrender in Berlin. Although Germany had surrendered to the Allies a day earlier, Stalin had insisted on a second surrender ceremony in Berlin.

As a military officer, Keitel was prohibited by law from joining the NSDAP (Nazi Party). However, after the Wehrmacht's rapid early successes on the Russian Front, he was given a "Golden" (Honorary) NSDAP membership badge by Adolf Hitler, who was seeking to link military successes to political successes. In 1944, German laws were changed and military officers were encouraged to seek NSDAP membership. Keitel claimed he did so as a formality at the Nuremberg Trials, but never received formal party membership. He was one of only two people to receive honorary party membership status.

Before his execution, Keitel published Mein Leben: Pflichterfüllung bis zum Untergang: Hitlers Feldmarschall und Chef des Oberkommandos der Wehrmacht in Selbstzeugnissen, otherwise known in English as In the Service of the Reich, and was later re-edited as The Memoirs of Field - Marshal Keitel by Walter Görlitz from a translation by David Irving as the author in 1965. Another work by Keitel later published in English was Questionnaire on the Ardennes offensive.

Four days after the surrender, Keitel was arrested along with the rest of the Flensburg government. He soon faced the International Military Tribunal (IMT), which charged him with a number of offences: Conspiracy to commit crimes against peace; Planning, initiating and waging wars of aggression; War crimes; and, Crimes against humanity.

Keitel testified that he knew many of Hitler's orders were illegal (for instance, he described the Night and Fog Decree as "the worst of all" the orders he'd been given) but claimed he was merely following orders in conformity to "the leader principle" (Führerprinzip). The IMT rejected this defence and convicted him on all charges. Because of his signature on orders which called for soldiers and political prisoners to be killed or disappeared, he was sentenced to death. To underscore the criminal rather than military nature of Keitel's acts, the Allies denied his request to be shot by firing squad. Instead, he was executed by hanging. Due to the drop of the hanging not being long enough to break his neck immediately, Keitel died of strangulation 24 minutes after he was dropped down the hatch. Keitel's last words were:

which translates roughly to: