A Captain, abbreviated to Capt., is a junior officer rank of the British Army and Royal Marines and in both services it ranks above Lieutenant and below Major. The rank is equivalent to a Lieutenant in the Royal Navy and to a Flight Lieutenant in the Royal Air Force. The rank of captain in the Royal Navy is considerably more senior (equivalent to the Army/RM rank of Colonel) and the two ranks should not be confused.
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 It was superseded by the rank of flight lieutenant on the following day.
During the First World War, some officers took to wearing similar jackets to the men, with the rank badges on the shoulder, as the cuff badges made them conspicuous to snipers. This practice was frowned on outside the trenches but was given official sanction in 1917 as an alternative, being made permanent in 1920 when the cuff badges were abolished.
In the British Empire this rank denotes an officer of a warship carrying at least 20 guns. A captain in the Royal Navy is responsible for discipline, navigation, and equipment. A post-captain is one whose name has been posted on a permanent list; a flag-captain commands an admiral's ship; a captain of the fleet is a temporary officer in charge of fleet discipline, and is equivalent to an adjutant in the army.
The captain of the gun is a petty officer in charge of a gang of men. A captain in the Army commands a company of infantry, troop of cavalry, or battery of artillery. He ranks between a lieutenant and a major. He is responsible for the arms, clothes, efficiency and discipline of his men, and recommends for promotion the non-commissioned officers. A captain in the Navy receives from £411 to £602 per annum, with allowances and share of prize-money. An Army captain has, according to regiment, receives £211 to £273. 
References / notes
Glossary of words and phrases
The above term is listed in our glossary of words and phrases of the Armed Forces of Great Britain during the Great War. Included are trench slang, service terms, expressions in everyday use, nicknames, the titles and origins of British and Commonwealth Regiments, and warfare in general. These words and phrases are contemporary to the war, which is reflected in the language used. They have been transcribed from three primary sources (see Contents). Feel free to expand upon and improve this content.
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