The Webley Revolver was, in various marks, the standard issue service pistol for the armed forces of the United Kingdom, the British Empire, and the Commonwealth from 1887 until 1963. The Mk VI, introduced in 1915 during the First World War, is perhaps the best-known model. Firing the large .455 Webley cartridge, Webley service revolvers are among the most powerful top-break revolvers ever produced. Although the .455 calibre Webley is no longer in military service, the .38/200 Webley Mk IV variant is still in use as a police sidearm in a number of countries.
On 24 May 1915, the Webley Mk VI was adopted as the standard sidearm for British and Commonwealth troops and remained so for the duration of the First World War, being issued to officers, airmen, naval crews, boarding parties, trench raiders, machine-gun teams, and tank crews.