Papers relating to his military service, including; RNVR Service Certificate (4pp, 1908 – 1911); a pass and a ticket to leave Germany (August 1914); papers relating to joining the 21st Battalion, County of London Regiment; correspondence with George Forbes, Earl of Granard, regarding getting a commission (December 1914); a commission certificate (December 1914); a discharge certificate on his appointment for a commission (February 1915); two memoranda from the Adjutant, 10th Battalion King's Own (Royal Lancaster Regiment) about Devenish's illness and kit he will need for joining the Regiment (January 1915); a pass to travel to Egypt (February 1916); papers relating to his promotion to Captain and travelling to Egypt, Mesopotamia and India with 2nd Battalion British West Indies Regiment (1916 – 1919), including memoranda to 181st Infantry Brigade (60th (London) Division) relating to training relating to Mesopotamia, and enemy secret agents; a copy of his marriage certificate (September 1919); newspaper clippings and letters relating to a reunion of the Regimental Association of the King's Own (RLR) (1937); correspondence relating to being initially turned down for the Intelligence Department, War Office, due to already being a member of the Officer's Emergency Reserve (October 1938 – June 1939); joining Military Intelligence and appointment as an interpreter at No 18 Internment Camp, Fontwell Park (June - July 1939); appointment as prisoner of war mail censor with MI1b with the BEF (December 1939); struck off following Dunkirk; appointment as Interpreter (Captain) at Arrow Park Aliens Camp, Birkenhead (July 1940); a memo he wrote about aerodrome defence; papers relating to his work in Northern Ireland with the Royal Ulster Constabulary, intercepting Cahir Healy MP's correspondence, with newspaper articles about Healy's arrest; papers relating to awards and decorations (1945 – 1948); menus and programmes for dances; papers relating to the Glasgow Dock Strike (1947) and an Army unit under Major Devenish unloading 46,000 tons of food; papers relating to his posting to 293rd German Prisoner of War Working Camp (January 1948); papers relating to his release from the Army (June 1948); a ts list of his service and appointments; and photocopies of pages from the London Gazette concerning his appointments. Together with a photocopy of an article (4pp, 2005) written by Captain H J Carter for the 'Intelligence Corps Journal' covering Devenish's personal history but focussing on his work in Northern Ireland intercepting Cahir Healy MP's correspondence, and is based on the papers plus research from the National Archive and other sources.
Military conflict took place during every year of the 20th Century. There were only short periods of time that the world was free of war. The total number of deaths caused by war during the 20th Century has been estimated at 187 million and is probably higher.