A battlegroup (British/Commonwealth term) or task force (U.S. term) in modern military theory is the basic building block of an army's fighting force. A battlegroup is formed around an infantry battalion or armoured regiment, which is usually commanded by a lieutenant colonel. The battalion or regiment also provides the command and staff element of a battlegroup, which is complemented with an appropriate mix of armor, infantry, and support personnel and weaponry relevant to the task it is expected to perform.
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The organization of a battlegroup is flexible and can be restructured quickly to cope with any situation changes. Typically, an offensive battlegroup may be structured around an armored regiment, with two squadrons of main battle tanks supported by an infantry company; conversely, a more defensive battlegroup may be structured around an infantry battalion, with two companies and an armored squadron. In support would be a reconnaissance troop, a low-level air defense detachment, an anti-tank section, engineering detachment, and artillery support.
Battlegroups are often subdivided into company groups (called "teams" in the U.S. Army) consisting of a single infantry company supported by a tank troop and various other support units.