William Mitchell, the son of the US Senator for the State of Wisconsin, was born in 1879. As a teenager he served as a soldier in the Spanish-American War. Mitchell remained in the army after the war and was sent as a military observer with the Japanese army during the Russo-Japanese War.

In 1914 Captain Mitchell was the youngest member of the War Department General Staff. During the next two years he became involved in the affairs of the Aviation Section. At 36 Mitchell was considered too old to attend the US Army Air Service training school at San Diego, and so he learnt to fly at his own expense.

On the outbreak of the First World War it was decided to send three officers to Europe to observe developments in aviation. Although Mitchell had only had fifteen hours of flying and no practical experience in military aviation, he was one of the three men chosen. Mitchell visited General Sir Hugh Trenchard at the headquarters of the Royal Flying Corps. The two men got on well together and Mitchell learnt a great deal from this experience.

General John Pershing arrived in France as leader of the American Expeditionary Forces in May 1917. Lieutenant-Colonel William Mitchell went to see Pershing and convinced him that he should become senior aviation officer on his staff.

Mitchell was given responsibility for the training and organization of the US pilots in France. The first US fighter patrols over German lines began in March 1918 and played an important role during action at St Mihiel and Meuse-Argonne.

In 1921 Mitchell was appointed Assistant Chief of the US Air Service. Mitchell disapproved of the air policies being pursued by the US Army and Navy Departments. In September 1925, he published an article in Aviation Magazine, where he criticized War and Navy Department mismanagement of the aviation service. Mitchell was court-martialled and convicted of insubordination. Sentenced to a 5-year rank suspension he left the Army in 1926.

Mitchell spent the rest of his life lecturing on subjects such as the future importance of strategic bombing. Mitchell also wrote several books on aviation including Winged Defence (1925) and Skyways (1930). After his death in 1936, William Mitchell was posthumously promoted and decorated.

Most of Mitchell's arguments were borne out during the Second World War and most of his suggestions were eventually adopted by the United States Air Force.