Army Group

Military organization
Typical units	Typical numbers	Typical commander
fireteam	3–4	corporal
squad/ section	8–12	sergeant
platoon	15–30	lieutenant
company	80–150	captain/major
battalion/ cohort	300–800	lieutenant colonel
regiment/ brigade	2,000–4,000	colonel/ brigadier general
division/ legion	10,000–15,000	major general
corps	20,000–40,000	lieutenant general
field army	80,000+	general
army group	2+ field armies	field marshal/ five-star general
region/ theater	4+ army groups	Six-star rank

Common military ranks in English
Navies	Armies	Air forces
Commissioned and Non-commissioned officers
Admiral of the fleet	Marshal or Field marshal	Marshal of the air force
Admiral	General	Air chief marshal
Vice admiral	Lieutenant general	Air marshal
Rear admiral	Major general	Air vice-marshal
Commodore	Brigadier or Brigadier general	Air commodore
Captain	Colonel	Group captain
Commander	Lieutenant colonel	Wing commander
Lieutenant commander	Major or Commandant	Squadron leader
Lieutenant	Captain	Flight lieutenant
Sub-lieutenant	Lieutenant or First lieutenant	Flying officer
Ensign	Second lieutenant	Pilot officer
Midshipman	Officer cadet	Flight cadet
Enlisted grades
Warrant officer or Chief petty officer	Warrant officer or Sergeant major	Warrant officer
Petty officer	Sergeant	Sergeant
Leading seaman	Corporal	Corporal
Seaman	Private	Aircraftman

An army group is a military organization consisting of several field armies, which is self-sufficient for indefinite periods. It is usually responsible for a particular geographic area. An army group is the largest field organization handled by a single commander—usually a full general or field marshal—and it generally includes between 400,000 and 1,000,000 soldiers.

In the Polish Armed Forces and former Soviet Red Army an army group was known as a Front. The equivalent of an army group in the Imperial Japanese Army was a "general army" (Sō-gun (総軍^?)).

Army groups may be multi-national formations. For example, during World War II, the Southern Group of Armies (also known as the U.S. 6th Army Group) comprised the U.S. Seventh Army and the French First Army; the 21st Army Group comprised the British Second Army, the Canadian First Army and the US Ninth Army.

In U.S. Army usage, the number of an army group is expressed in Arabic numerals (e.g., "12th Army Group"), while the number of a field army is spelled out (e.g., "Third Army").

The French Army formed a number of groupe d'armees during the First World War. The first of these was Army Group North, formed on a provision basis in October 1914. Army Group East and Army Group Centre both followed in 1915 while Army Group Reserve was established in 1917. A Franco-Belgian Army Group Flanders also existed briefly in 1918, under the command of Albert I of Belgium.

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Wikipedia