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First Division Museum


 Unit History Collection

Within the extensive military history collection at the Robert R. McCormick Research Center there is a special collection of the histories of individual military units. These unit histories were written by: individual soldiers, military historians, and Army personnel; they may be authorized or unauthorized accounts of a unit’s actions. Some unit histories cover a single action in a war; others may cover the whole history of a unit to date. Many of the unit histories in this collection of 500 plus titles are rare and unique to our Research Center. They represent actions from before the First World War up to the Iraq War, and we are always adding to the collection as new materials are written and published.Unit Histories may contain, in addition to the “story” of the unit, information on citations for decorated soldiers, lists of officers, names of soldiers who were killed in action, wounded in action, or who were missing in action, rosters of soldiers in a unit, maps, and photographs.

Our Unit Histories are used for research by veterans and their families, soldiers, authors, historians, students, and genealogists. Members of the staff of the McCormick Research Center welcome your questions.

For further information on the unit history collection or to use the collection, contact:

Reference Librarian
Mary Manning


Tracy Cirar



 Definitions (U.S. Army)

(Some Terms Used in this Database)

Army – Large land force consisting typically of two or more corps and a headquarters section.
Artillery – Any of several long-range, fairly large caliber guns (such as, howitzer, anti-aircraft, mortars, or anti-tank).
Battery – Tactical and administrative artillery unit or subunit corresponding to a company or similar Army unit.
Battalion – Four or more companies plus a headquarters section under the command of a lieutenant colonel.
Brigade – Three or more battalions plus a headquarters section under the command of a colonel; between 4,000 and 5,000 personnel; capable of independent military operation.
Cavalry – Army component normally mounted in motor vehicles or helicopters and assigned to combat missions that require great mobility, such as reconnaissance or security for a larger unit. Historically refers to troops that served on horseback.
Company – Unit under a captain’s charge that is made up of a headquarters section and two or more platoons. A company is the basic element of the battalion.
Corps – Tactical military unit, intermediate between a division and an army, consisting of two or more divisions and auxiliary arms and services.
Division – Combined group of tactical and administrative units that form a self-contained and fully equipped organization capable of sustained combat operations. Typically consists of headquarters and two or three brigades (12,000-20,000 troops) with artillery, combat support and combat service support units under the command of a major general.
Engineers – Combat branch of the Army; units responsible for construction and demolition in support of mobility, counter-mobility, and survivability.
Infantry – Personnel and units who close with the enemy by means of fire and maneuver in order to destroy or capture, or to repel assault by fire, close combat, and counter-attack. May fight dismounted or mounted according to mobility means provided.
Platoon – Second smallest military organizational unit. In the infantry, usually composed of four squads under the command of a lieutenant with a sergeant as second-in-command. Usually has forty men. Four platoons and a headquarters section form a Company.
Regiment – Military unit that consists of two or more battalions of ground troops; at a command level below a division and above a battalion.
Signal Corps – Combat support branch and personnel responsible for establishing and maintaining communications networks.
Squad – Smallest organizational unit. In the infantry usually consists of ten men under the command of a staff sergeant. Four squads make up a platoon.
Squadron – Battalion-size armored cavalry unit.
Troop – Cavalry unit at a command level below a squadron; equivalent to a company or battery.




























Dictionary of United States Army Terms (Short Title: AD). Headquarters, Department of the Army. 1983.

































Credits:  Unit Histories database created by Mary Manning