Fairbairn served with the Royal Marine Light Infantry starting in 1901, and joined the Shanghai Municipal Police (SMP) in 1907. During his service with the International Police in Shanghai, Fairbairn reportedly engaged in hundreds of street fights in the course of his duties over a twenty-year career, where he organised and headed a special anti-riot squad. Much of his body, arms, legs, torso, even the palms of his hands, was covered with scars from knife wounds from those fights.:p:191 Fairbairn later created, organised and trained a special anti-riot squad for the Shanghai police force, as well as developing numerous firearms training courses and items of police equipment, including a special metal-lined bulletproof vest designed to stop high-velocity bullets from the 7.63x25mm Mauser pistol.:p:191
During World War II, he was recruited by the British Secret Service as an Army officer, where he was given the nickname “Dangerous Dan”. Together with fellow close-combat instructor Eric Sykes, Fairbairn was commissioned on the General List in 1941. He trained British, American and Canadian Commando forces, along with Ranger candidates in close-combat, pistol-shooting and knife-fighting techniques. Fairbairn emphasised the necessity of forgetting any idea of gentlemanly conduct or fighting fair: “Get tough, get down in the gutter, win at all costs… I teach what is called ‘Gutter Fighting.’ There’s no fair play, no rules except one: kill or be killed,” he declared.:p:192
For his achievements in training OSS personnel, Fairbairn eventually rose to the rank of Lieutenant-Colonel by the end of the war, and received the U.S. Legion of Merit (Officer grade) at the specific request of “Wild Bill” Donovan, founder of the U.S. O.S.S.
After joining the SMP, he studied boxing, traditional jujutsu and then Chinese martial arts. He developed his own fighting system—Defendu—and taught it to members of that police force in order to reduce officer fatalities. He described this system as primarily based on his personal experience, which according to police records included some 600 non-training fights, by his retirement at age 55 from the position of Assistant Commissioner in 1940.
Together with Eric A. Sykes he developed innovative pistol shooting techniques and handgun specifications for the SMP which were later disseminated through their book Shooting To Live With The One-Hand Gun (1942), along with various other police innovations such as riot batons, armoured vests and other equipment.
He is perhaps best known for designing the famous Fairbairn-Sykes fighting knife, or ‘Commando‘ knife, a razor-sharp stilletto-style fighting dagger used by British Special Forces in the Second World War, and featured in his textbook Scientific Self-Defence.:p:191 Fairbairn also designed the lesser known Smatchet, and collaborated on the design of several other combat knife designs.
- Defendu, first published in 1926 in Shanghai by the North China Daily News & Herald Ltd. Size 7” X 10”, hardcover, cloth bound with 171 pages.
- Scientific Self-Defence, first published in 1931 by D. Appleton and Company New York & London. Size 6 ½” X 9 ½”, in hardcover with 165 pages. A slightly modified/updated version of Defendu.
- All-In Fighting, first published in 1942 by Faber and Faber Limited London. Size 5 ½” X 8 ¼” in hardcover with 132 pages.
- Get Tough, first published in 1942 by D. Appleton-Century Company New York & London. Size 5 ½” X 7 ¾” in softcover with 121 pages. This is a modified version of All-In Fighting for the American market. Note the first edition has Fairbairn’s rank as ‘Captain’ all subsequent (1940’s) editions as ‘Major’.
- Self Defence for Women and Girls, first published in 1942 by Faber and Faber London. Size 5 ½” X 8” softcover with 48 pages.
- Hands Off! (Self Defence for Women and Girls), first published in 1942 by D. Appleton-Century Company New York & London. Size 5 ¼” X 8” in softcover with 41 pages. This is a modified version of Self Defence for Women and Girls for the American market.
- Shooting to Live, co-authored by Eric Anthony Sykes, first published in 1942 by Oliver and Boyd London England. Size 4 ¾” X 7″ in hardcover with 96 pages.