A battalion is a military unit that is typically composed of 300 to 1,000 soldiers and commanded by a lieutenant colonel. It is subdivided into a number of companies, usually commanded by a major or a captain. A battalion comprises two or more primary mission companies, which are often of a common type, such as infantry, tank, or maintenance. In addition to the primary mission companies, a battalion typically includes a headquarters staff and combat service support, which may be combined into a headquarters and service company. A battalion can conduct independent operations of limited scope and duration and is usually commanded by a lieutenant colonel. There are combat arms battalions, as well as combat support and combat service support battalions. The term "battalion" is used in the British Army Infantry and some corps, including the Royal Electrical and Mechanical Engineers and Intelligence Corps. In the Canadian Army, the battalion is the standard unit organization for infantry and combat service support, and each battalion is divided into one or more sub-units referred to as companies.