Army Unit Sizes - WWII
This is a rough approximation of regular army units. "Bastard" or independent engineer regiments vary somewhat from this. More on this later in this post...
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Squad - 9 to 10 soldiers. Typically commanded by a sergeant or staff sergeant, a squad or section is the smallest element in the Army structure, and its size is dependent on its function.
Platoon - 16 to 44 soldiers. A platoon is led by a lieutenant with an NCO as second in command, and consists of two to four squads or sections.
Company - 62 to 190 soldiers. Three to five platoons form a company, which is commanded by a captain with a first sergeant as the commander's principle NCO assistant. An artillery unit of equivalent size is called a battery, and a comparable armored or air cavalry unit is called a troop.
Battalion - 300 to 1,000 soldiers. Four to six companies make up a battalion, which is normally commanded by a lieutenant colonel with a command sergeant major as principle NCO assistant. A battalion is capable of independent operations of limited duration and scope. An armored or air cavalry unit of equivalent size is called a squadron.
Brigade/Regiment - 3,000 to 5,000 solders. A brigade headquarters commands the tactical operation of two to five organic or attached combat battalions. Normally commanded by a colonel with a command sergeant major as senior NCO, brigades are employed on independent or semi-independent operations. Armored cavalry, ranger and special forces units this size are categorized as regiments or groups.
Division - 10,000 to 15,000 soldiers. Usually consisting of three brigade-sized elements and commanded by a major general, divisions are numbered and assigned missions based on their structures. The division performs major tactical operations for the corps and can conduct sustained battles and engagements.
Corps - 20,000 to 45,000 soldiers. Two to five divisions constitute a corps, which is typically commanded by a lieutenant general. As the deployable level of command required to synchronize and sustain combat operations, the corps provides the framework for multi-national operations.
Army - 50,000 + soliders. Typically commanded by a lieutenant general or higher, an army combines two or more corps. A theater army is the ranking Army component in a unified command, and it has operational and support responsibilities that are assigned by the theater commander in chief. The commander in chief and theater army commander may order formation of a field army to direct operations of assigned corps and divisions. An army group plans and directs campaigns in a theater, and is composed of two or more field armies under a designated commander. Army groups have not been employed by the Army since World War II.
Above Information Derived from DA Pamphlet 10-1
There is no set size (number of troops) assigned to any specific element. The size of an element of command depends primarily upon the type of unit and mission. For example, an aviation company would have a different number of troops assigned than an infantry company because it has a different mission, different equipment, and therefore different requirements.
Note: The usual structure is battalion -> brigade -> division, with battalions organized into regiments as the exception. An example of this exception would be cavalry regiments. Cavalry is unique in that battalions are called "squadrons" and companies are called "troops."
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Army - 2 or more corps
Corps - 2 or more divisions
Division - 3 or more regiments or brigades
Regiment - 3 battalions (two in some engineer units)
Battalion - 3 companies
Company - 3 to 4 platoons
Platoon - roughly 24 men
Squad - approximately 8 men
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Engineer units (separate)
I hope you will find the following helpful. I've shared this army lesson a few times over the past few years. Welcome to the army!
This is using the VI Corps engineer units as an example. This may help you "picture" it. Each of the "bastard" or separate engineer units were all regiments. Each regiment has either two to three battalions, each battalion has three companies, plus HQ, H&S Co's, Medical detachments, etc. Here's a breakdown for the four units I am researching:
36th Engineer Regiment - 2826, 2827, 2828th Battalions
2826th - A, B and C Companies
2827th - D, E and F Companies
2828th - G, H and I Companies
39th Engineer Regiment - 1st and 2nd Battalions
1st - A, B and C Companies
2nd - D, E and F Companies
540th Engineer Regiment - 2832nd and 2833rd Battalions
2832nd - A, B and C Companies
2833rd - D, D, and F Companies
1108th Engineer Regiment - 48th and 235th Battalions
48th - A, B and C Companies
1108th - D, E, and F Companies
Many times companies were in the same area, but each company within a regiment could be given different assignments, so they did not necessarily work together.
A company was further broken down into the following:
1 company = 3 to 4 platoons
1 platoon = 3 squads
My dad was - 540th Combat Engineer Regiment (or later in the war, Group), 2833rd Battalion, H&S Company, 4th Platoon
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You will notice that everyone of the above engineer regiments had only two battalions, except for the 36th Engineer Regiment, which had the NORMAL three army battalions. As you can see, the ARMY loves the number three! This is not an accidental number, but allows the the "use" of two at the front (in action), while the other battalion remains in reserve (at rest).
Lesson over, class dismissed!