John Slessor

Marshal of the Royal Air Force Sir John Cotesworth (Jack) Slessor GCB, DSO, MC (3 June 1897 – 12 July 1979) was a senior commander in the Royal Air Force (RAF), serving as Chief of the Air Staff from 1950 to 1952. As a pilot in the Royal Flying Corps during World War I, he saw action with No. 17 Squadron in the Middle East, earning the Military Cross, and with No. 5 Squadron on the Western Front, where he was awarded the Belgian Croix de Guerre. Between the wars he commanded No. 4 Squadron in England, and No. 3 (Indian) Wing, earning the Distinguished Service Order for operations with the latter in Waziristan. In 1936, he published Air Power and Armies, examining of the use of air power against targets on and behind the battlefield.

Slessor held several operational commands in World War II. As Air Officer Commanding Coastal Command in 1943 and 1944, he was credited with doing "much to start winning the Battle of the Atlantic" by his use of long-range bombers against German U-boats. He was knighted in June 1943. In the closing stages of the war he became Commander-in-Chief RAF Mediterranean and Middle East and deputy to Lieutenant General Ira Eaker as Commander-in-Chief Mediterranean Allied Air Forces, conducting operations in the Italian Campaign and Yugoslavia. Slessor went on to serve in the RAF's most senior post, Chief of the Air Staff, in the early 1950s, and was considered a strong proponent of strategic bombing and the nuclear deterrent. In retirement he published two more books, including an autobiography, and held appointments with Somerset County Council.

World War I
The son of Major Arthur Kerr Slessor and Adelaide Slessor (née Cotesworth), Slessor was educated at Haileybury. Lame in both legs as a result of polio, he was rejected for army service in 1914 and only received a commission as a second lieutenant in the Royal Flying Corps on 6 July 1915 with the help of family connections. He was appointed to the special reserve as a flying officer on 9 September 1915. He saw action with No. 17 Squadron in Egypt and the Sudan, where he was credited with arresting the escape of Sultan Ali Dinar with 2,000 men on 23 May 1916, following the Sultan's defeat at Beringia. He was mentioned in despatches on 25 October 1916 before being wounded in the thigh and invalided back to England.

Slessor was promoted to the temporary rank of captain on 1 December 1916. Awarded the Military Cross on 1 January 1917, he returned to combat in April 1917 as a flight commander with No. 5 Squadron on the Western Front. Promoted to the substantive rank of lieutenant on 1 July 1917, he was appointed a Knight of the Belgian Commander of the Order of Leopold on 24 September 1917 and awarded the Belgian Croix de Guerre on 11 March 1918. Slessor joined the newly formed Royal Air Force in April 1918 and, having been promoted to the temporary rank of major on 3 July 1918, he was posted to the Central Flying School as an instructor on 14 July 1918.

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 [this book] 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.

World War II
Slessor was promoted air commodore on the first day of World War II, 1 September 1939. On 10 January 1941, he was raised to temporary air vice marshal (made permanent in April 1942) and became Air Officer Commanding No.5 (Bomber) Group in May 1941. Appointed a Companion of the Order of the Bath and mentioned in despatches in January 1942, he was appointed Assistant Chief of the Air Staff in April 1942. Slessor was closely involved in planning the combined Allied air offensive in Europe. At the Casablanca Conference in January 1943, he was able to influence Britain's Secretary for Air, Sir Archibald Sinclair, and Chief of the Air Staff, Air Chief Marshal Sir Charles Portal, to agree to USAAF proposals that led to a 'round-the clock' bombing policy against Germany, with the US mounting daylight precision attacks and the RAF conducting area bombing at night.

Appointed AOC Coastal Command with the acting rank of air marshal on 5 February 1943, Slessor was credited with doing "much to start winning the Battle of the Atlantic", employing his thinly stretched long-range bomber force against the U-boat threat, in close cooperation with naval forces. Promoted temporary air marshal on 1 June 1943, he was advanced to Knight Commander of the Order of the Bath in the 1943 Birthday Honours. He went on to become Commander-in-Chief RAF Mediterranean and Middle East in January 1944, and deputy to Lieutenant General Ira Eaker as Commander-in-Chief Mediterranean Allied Air Forces. In this role he conducted operations in the Italian Campaign and Yugoslavia, establishing the Balkan Air Force in the latter theatre. Slessor was made Air Member for Personnel on 5 April 1945, his rank of air marshal becoming substantive on 6 June 1945.

He was awarded the Grand Cross of the Greek Order of the Phoenix on 6 September 1946 and appointed a Commander of the Belgian Order of Leopold on 27 August 1948.

Post-war career
Slessor was promoted air chief marshal on 1 January 1946. He remained in the post of Air Member for Personnel until the end of 1947, when he succeeded General Sir William Slim as Commandant of the Imperial Defence College, at the urging of the-then Chief of the Air Staff, Marshal of the Royal Air Force Sir Arthur Tedder. Slessor had been dubious about accepting the position, and sought assurances from Tedder that he would be next in line for the Chief of the Air Staff post, particularly in light of Tedder's preference for Air Chief Marshal Sir Ralph Cochrane to succeed him. Meanwhile Slessor also became Principal Air Aide-de-Camp on 1 July 1948. In the event, Slessor took over from Tedder as Chief of the Air Staff on 1 January 1950, and chose Cochrane as his Vice Chief of the Air Staff. Having been appointed a Knight Grand Cross of the Bath on 10 June 1948, he was promoted Marshal of the Royal Air Force on 8 June 1950. In late 1951, Slessor reluctantly became involved in the Australian Government's quest for a suitable RAF officer to serve as Chief of the Air Staff of the Royal Australian Air Force. He eventually selected Air Marshal Sir Donald Hardman as the "outstanding candidate" for the Australian post, trying to avoid what he called "the follies of some years ago", referring to Air Chief Marshal Sir Charles Burnett's controversial tenure as Chief of the Air Staff in Australia on secondment from Britain in the early years of World War II.

As leader of the RAF, Slessor coined the term 'V-Force' to denote the its planned trio of strategic jet bombers: the Vickers Valiant, Handley Page Victor, and Avro Vulcan, and contributed to the more expensive but safer decision to build all three designs. He played a key role in promoting nuclear weapons as an effective instrument of deterrence in early Cold War British strategy. In 1952, the RAF argued that, because bombers were such an important deterrent, conventional forces could be drastically reduced at a time when the Government was seeking significant public expenditure savings. Slessor believed it unlikely that the United Kingdom would be able to meet a communist offensive without resorting to the use of tactical nuclear weapons. He became one of the key propagandists of the 'Great Deterrent' (which he employed as the title of a book he wrote after he retired) on both sides of the Atlantic. Slessor's tour as Chief of the Air Staff was dominated by the Korean War.

Later life
Slessor completed his term as Chief of the Air Staff on 31 December 1952 and retired from the RAF in the new year. He attended the coronation of Queen Elizabeth II in June 1953. He published two books in retirement: his autobiography, The Central Blue (1956), and The Great Deterrent (1957). He also served as Honorary Air Commodore of No. 3 (County of Devon) Maritime Headquarters Unit Royal Auxiliary Air Force from 23 May 1963.

A member of Somerset County Council from 1963 to 1974, Slessor served as High Sheriff of Somerset from 1962 to 1966. He was appointed Deputy Lieutenant of Somerset in 1969. Following the death of his first wife, Hermione Grace Guinness, he married Marcella Florence Priest (née Spurgeon) in 1971. Slessor died at the Princess Alexandra Hospital, Wroughton in Wiltshire on 12 July 1979. His son John also joined the RAF, rising to the rank of group captain.