Brandon's Notepad

October 9, 2013

Military Operational Units

Home > My Research > History > Military History > Military Operational Units

At first glance, the names of military operational units appear to be quite arbitrary. What’s the difference between a battalion, a brigade, and a division anyway? What do these things mean? How am I supposed to know that one is bigger than another? I wrestled with these questions every time I turned the pages of a war novel or read about the successful operation conducted by this unit or that one. Finally, I decided to dig deeper, to find the rhyme and reason behind military organization.

I recall reading somewhere in military literature about the most atomic military units being comprised of two or three men and how all larger units are built using these basic building blocks. I cannot find the source now, but when I do, I will update this post. Regardless, this point inspired me to list the units beginning with the smallest and working upward, the opposite order in which they are usually listed.

The names of the units are revealing, most of which have been in use since the late 16th & early 17th centuries, and are derived from Latin or other Romantic language. Regarding the number of units that combine to form a larger unit, the magic number appears to be three. As a starting point, I began with a current list of U.S. military operational units. The etymologies of the names are based on the entries found in the Online Etymology Dictionary.

Squad. This is the smallest unit. Usage originating (c. 1640s) in the Romantic languages and in Latin, it literally means “square”, denoting the formation in which the men would fight. Immediately, the Roman testudo formation comes to mind. In the U.S., the size of a squad ranges from 4 to 10 members, and is headed by a Staff Sergeant, the word sergeant meaning “servant”.

Platoon. Three squads (maybe four) comprise a platoon. The name comes from (c. 1630s) the French word peloton which refers simply to “a group of people”. A platoon is led by a Lieutenant, which means “substitute” (“in lieu of” + “tenant” which means holding, so literally, a placeholder)

Company. Three (or four) platoons comprise a company, which also refers to a “large group of people”. The word comes from (c. 1580) Old French compagnie & Latin companio. A company is led by a Captain, meaning a “leader” or “chief”, from the Latin caput which means “head”.

Just for reference, the rank of Major falls between Captain and Lt. Colonel.

Battalion. Three to five companies form a battalion. It is led by a Lieutenant Colonel. Following the general guidelines provided on the page linked above for U.S. units, the number of men in a battalion should range mathematically from 108 to 800; however, the range listed for this unit is 500 to 600. Either way, this number give some indications as to how many soldiers are needed to win a battle, since the term originates from 16th Century French/Italian and means “battle squadron”.

Three battalions form a brigade. For U.S. units, this means three-thousand to five-thousand troops. In French the word means a “body of soldiers”, but in Italian it is used in a more general sense to refer to a troop or a gang. A Colonel leads a brigade in the U.S. (or a Colonel General in some countries). This is an Italian title referring to the commander of a column (of soldiers). More traditionally (c. 1670s), the leader was a Brigadier General.

Regiment. The unit known as a regiment is defined very loosely. Its size is not specific, but varies by country and can range from a Company to a Brigade.

Division. Three brigades form a division, ten-thousand to eighteen-thousand members headed by a Major General. Though this term is very generic and part of common speech today, it was first used in military terms in the 1590s.

Corps. Two to five divisions comprise a corps, headed by a Lieutenant General. First used in English in 1704, it is shorthand for the (c. 16th C) French phrase corps d’armée. Pronunciation has varied over time, but “core” seems to be the proper and most common way to say the word in English.

Field Army. An army is two or three corps led by a General. from French (armée) and Latin (armata), it basically means “armed force”. It first applied specifically to a land-based force in 1786. In the States, citizens will immediately associate the term with the U.S. Army in general; however, the U.S. has employed multiple armies in its history (think: Patton’s Third Army).

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