In the 21st-century British Army, captains are often appointed to be second-in-command of a company or equivalent sized unit of up to 120 soldiers.
A rank of second captain existed in the Ordnance at the time of the Battle of Waterloo.
From 1 April 1918 to 31 July 1919, the Royal Air Force maintained the junior officer rank of captain. RAF captains had a rank insignia based on the two bands of a naval lieutenant with the addition of an eagle and crown above the bands. It was superseded by the rank of flight lieutenant on the following day.
Badges of rank for captains were introduced on 30 January 1855 and were worn on shoulder epaulets. After the Crimean War a new rank system was introduced which contained the first complete rank insignia in British Army history. A captain's rank insignia was worn on the collar and displayed a crown and a pip (which is now the rank insignia for a lieutenant-colonel).
1856 to 1880 captain's rank insignia
The rank insignia were returned to the shoulder boards in 1880 for all officers in full dress, when the system of crowns and stars was reorganised. From this time, until 1902, a captain had just two stars. The 1902 change gave captains three stars, which continues to be used. In addition to the shoulder badges, officers' ranks were also reflected in the amount and pattern of gold lace worn on the cuffs of the full-dress tunic.
1881 to 1902 captain's rank insignia