Lieutenant John Steel (Jock) Lewes (21 December 1913 – 31 December 1941) was a British Army officer prominent during World War II. He invented an explosive device, the eponymous Lewes bomb, and was the founding principal training officer of the Special Air Service. Its founding commander, David Stirling said later of Lewes: "Jock could far more genuinely claim to be founder of the SAS than I."
He attended at Christ Church College, Oxford. Lewes was president of the Oxford University Boat Club 1936–37, but gave up his place in the 1937 Blue boat which ended up winning the 1937 University Boat Race, ending a 15-year Cambridge winning streak. While an undergraduate, Lewes traveled to Germany and became an admirer of Hitler and the Nazi State, before casting off his illusions after the events of Kristallnacht. 
Lewes was first commissioned as a Second Lieutenant, University Candidate, General List in 1935, whilst a student at Oxford. After graduation he transferred to a Territorial Army unit, 1st Battalion, the Tower Hamlets Rifles, Rifle Brigade before joining the Welsh Guards.
In 1941, Lewes was in a group of volunteers assembled by Lieutenant David Stirling to form a unit dedicated to raiding missions against the lines of communication of Axis forces in North Africa. For counter-espionage purposes, this platoon-sized was initially named "'L' Detachment, Special Air Service Brigade".
To destroy Axis vehicles, members of the SAS surreptitiously attached small explosive charges. Lewes noticed the respective weaknesses of conventional (blast) and incendiaries, as well as their failure to destroy vehicles in some cases. He improvised a new, combined charge out of plastic explosive and cans of petrol. The Lewes bomb was used throughout World War II.
Jock Lewes was killed in action in December 1941. He was returning from a raid on German airfields when the Long Range Desert Group truck he was traveling in was attacked by a lone Messerschmitt 110 fighter. Lewes was fatally wounded in the thigh by a 20mm round from the fighter and bled to death in about four minutes. He was buried on the site where the attack happened but the whereabouts of his grave are now unknown. He is commemorated on the Alamein Memorial.
Lewes was engaged to marry Mirren Barford, an Oxford undergraduate, at the time of his death.
- Army News [Australia], 11 January 1945, p3.
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