John Slessor - Inter-war Years

Inter-war Years

Having left the RAF in 1919, Slessor applied to rejoin the following year and was offered a short-service commission as a flight lieutenant on 24 February 1920. He became a flight commander with No. 20 Squadron flying Bristol biplanes over the North West Frontier of India in May 1921 and then joined the staff at the Directorate of Training and Staff Duties in the Air Ministry in February 1923. In 1923 he married Hermione Grace Guinness; they had one son and one daughter. He attended the RAF Staff College in 1924 and was then promoted to squadron leader on 1 January 1925.

Slessor served as Officer Commanding No. 4 Squadron flying Bristol biplanes from RAF Farnborough from April 1925 to October 1928, when he joined the air planning staff at the Directorate of Operations and Intelligence in the Air Ministry. After attending the Staff College, Camberley in 1931, he was appointed RAF Directing Staff Officer there in January 1932. He was promoted to the acting rank of wing commander on 1 January 1932 (substantive on 1 July 1932). He became Officer Commanding No. 3 (Indian) Wing in March 1935, and was awarded the Distinguished Service Order for operations in Waziristan.

Slessor authored Air Power and Armies, an examination of the use of air power against targets on and behind the battlefield, in 1936. In this work he advocated army co-operation, interdiction to cut off enemy reinforcements and supply, and the use of aerial bombardment as a weapon against enemy morale. He did, however, acknowledge the limitations of his theory, stating:

...the conditions envisaged throughout are those of a campaign on the land in which the primary problem at the time is the defeat of an enemy army in the field. ... in a war against a great Naval power at sea, or when the principle threat to the Empire at the time is the action of hostile air forces against this country or its possessions, the aim and objectives of the air forces of the Empire will not be the same as described in this book.

On 17 May 1937, following his posting to India, Slessor was granted the acting rank of group captain, and appointed Deputy Director of Plans at the Air Ministry. He was promoted to substantive group captain on 1 July 1937. Mentioned in despatches on 18 February 1938, he took over as Director of Plans on 22 December 1938. He was appointed Air Aide-de-Camp to the King on 1 January 1939.