Captain ( armed forces ) The army rank of captain ( from the French " capitaine " ) is a commissioned officer rank historically corresponding to command of a company of soldiers . The rank is also used by some air force s and marine forces . Today a captain is typically either the commander or second - in - command of a company or artillery battery ( or United States Army cavalry troop or Commonwealth squadron ) . In the Chinese People ' s Liberation Army , a captain may also command a company , or be the second - in - command of a battalion . In NATO countries the rank of captain is described by the code OF - 2 and is one rank above an OF - 1 ( lieutenant or first lieutenant ) and one below an OF - 3 ( major or commandant ) . The rank of captain is generally considered to be the highest rank a soldier can achieve while remaining in the field . In some militaries such as United States Army and Air Force and the British Army , captain is the entry - level rank for officer candidates possessing a professional degree , namely medical professionals ( doctors , nurses , pharmacists , dentists ) and lawyers . The rank of captain should not be confused with the naval rank of captain or with the British - influenced air force rank of group captain , both of which are equivalent to the army rank of colonel . History . Prior to the professionalization of the armed services of European nations subsequent to the French Revolution , a captain was a nobleman who purchased the right to head a company from the previous holder of that right . He would in turn receive money from another nobleman to serve as his lieutenant . The funding to provide for the troops came from the monarch or his government ; the captain had to be responsible for it . If he was not , or was otherwise court - martialed , he would be dismissed ( " cashiered " ) , and the monarch would receive money from another nobleman to command the company . Otherwise , the only pension for the captain was selling the right to another nobleman when he was ready to retire . Air forces . In most countries the air force is the junior service and so air force ranks have been adopted or modified from one of the other services . Many , such as the United States Air Force , use a rank structure and insignia similar to those of the army . However , the United Kingdom ' s Royal Air Force , many other Commonwealth air forces and a few non - Commonwealth air forces use an air force - specific rank structure in which flight lieutenant is OF - 2 . A group captain is OF - 5 and was derived from the naval rank of captain . In the unified system of the Canadian Forces the air force rank titles are identical to that of the army as are army and air rank insignia with both wearing two gold stripes on the sleeve or epaulette . While the rank is equivalent to a naval lieutenant , naval lieutenant rank insignia is embellished with the executive curl . The modern equivalent of the British group captain bears the rank and insignia of colonel , i . e . four gold stripes on sleeve or epaulette ( same as a naval captain ) . Equivalent Captain ranks . Israel Defense Force ( IDF ) . In the Israel Defense Force ( IDF ) , since 1948 , סרן Seren is equivalent to a Captain ( OF - 2 ) . " Seren " translates as " Captain " or " Military Commander " . Typically it is the rank of a Company or Battery Commander . The rank above Captain is Rav seren ( Rasan , Major ) . Note that the IDF uses this rank across all three of its services . Insignia . A variety of images illustrative of different forces ' insignia for captain ( or captain - equivalents ) are shown below :