A battalion, in many armies, is a unit consisting of between 500 and 1500 men. A battalion is typically organised into companies, and is commanded by a Lieutenant Colonel. In some countries, the term battalion is used only for infantry units, while others also use it for tank and cavalry units. Several battalions may be organised into a regiment or a brigade.
In the British Army, the various infantry regiments are presently organised into 36 battalions. The Royal Logistics Corps, Royal Army Medical Corps and Royal Electrical and Mechanical Engineers (REME) are also organised into battalions. A battalion is always commanded by a Lieutenant Colonel, with a Major as second-in-command (2IC). It is normally subdivided into five companies; HQ (Headquarters) company, a manouevre support company (which provides fire support using mortars, machine guns, snipers, etc.), and three rifle companies. Each company is commanded by a Major.
United States Army
Battalions are also used in the United States Army and United States Marine Corps.