Division

Early History

Divisions have constituted a significant type of military organization in the West since the mid-1700s. The idea originated with the Royal French Army to divide a field army into self-contained “divisions,” which, for a limited time, could both march and fight independently. The French marshall de Broglie experimented with divisions composed of several brigades in the Seven Years’ War.

General George Washington ordered the army at Boston to be organized into three divisions of two brigades on July 22, 1775. While initially organized as administrative general officer commands, both divisions and brigades, composed of several habitually assigned infantry regiments and an artillery battery, evolved into semipermanent tactical organizations capable of operating jointly or separately. As the war progressed, Washington maneuvered the divisions independently to conduct operations away from the main army.

The U.S. Army continued to use divisions as a wartime formation during the 19th century. The army employed ad hoc divisions during both the War of 1812 and the Mexican-American War. Influenced by Napoleonic tactics, during the American Civil War, both sides employed divisions as the intermediate tactical headquarters between brigade and corps.

Following the hasty organization and deployment for the War with Spain, the army created its first peacetime combined arms division, the “Maneuver Division,” in March 1911. However, it was not until June 8, 1917, that the army formed its first permanent division, the 1st Expeditionary Division (later the 1st Infantry Division). During World War I, the U.S. Army designed its “square divisions” for sustained battle with some 28,000 men assigned. Forty-three Infantry Divisions served in Europe during World War I, including the 2nd Division with a Marine Brigade.

World War II and Korean War

During World War II, the United States fielded an array of divisions. The army employed 66 “triangular” infantry divisions, composed of three infantry regiments and nine infantry battalions, as a lean but standardized building block of more than 14,000 organic or permanently assigned personnel for global war in both European and Pacific theaters. Sixteen Armored, five Airborne, one Mountain, and one Cavalry Division (serving dismounted) rounded out the U.S. Army’s combat divisions. By 1944, 14 of the Armored Divisions were flexible organizations of almost 11,000 men with three each tank, armored infantry, and self-propelled artillery battalions organized under three combat commands. In the Pacific, the U.S. Marine Corps also provided six large divisions of more than 20,000 men designed as the ground combat element of Marine Air Ground Teams for amphibious operations.

Based on lessons learned in World War II, the army reorganized its infantry divisions for the Korean War. While the divisional structure retained three infantry regiments, the eight infantry divisions that fought were larger at approximately 19,000 and included an organic tank battalion. After Korea, the army flirted with a radical redesign for nuclear war, the Pentomic Division. This structure reduced the size of infantry divisions back to 14,000 men, replaced the previous structure with five battle groups of five rifle companies each, but added organic nuclear-capable artillery and an aviation company.

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