Assessment of the Legion as the Ideal Small Wars Force Structure
This article is published as part of the Small Wars Journal / Divergent Options Writing Contest which ran from March 1, 2019 to May 31, 2019.
After the Massacre at the Wabash in 1791, George Washington and Henry Knox reformed the U.S. Army as the Legion of the United States. The Legion was a self-contained modular army composed of four identical combined-arms units. During the Fallen Timbers campaign, the Legion proved itself the ideal force structure for use in small wars. The Brigade Combat Team is the closest the U.S. Army has ever come to reviving the legionary structure.
In 1791 the United States Army suffered one of the greatest defeats in its history. At the Massacre at the Wabash in modern Ohio, also known as St. Clair’s Defeat, a force of regulars and militia 1,000 strong was destroyed by an army of Indian warriors. The Northwest Indian War, as the greater conflict was called, was the definitive “small war.” President George Washington directed and oversaw the response: a punitive use of asymmetric military force against a loosely-organized tribal confederacy in contested territory. The Battle of Fallen Timbers in 1794 was the climax of the war, in which a reformed American army routed its Indian opponents and forced a peace where one could not be negotiated.
But in 1791 the path to victory was far from clear. Year after year, American forces marched into the Northwest Territory only to be beaten back by an aggressive, experienced, and knowledgeable enemy. George Washington and Secretary of War Henry Knox knew that significant change had to be made if the status quo was to be overcome. Tactical changes would not suffice. A redesign of the core force structure of the United States Army was required.
The inspiration for Washington and Knox’s reformed army came from four primary sources: Ancient Rome, French Marshal Maurice de Saxe, British Colonel Henry Bouquet, and Washington’s famous drillmaster, the Prussian Baron Frederick William von Steuben.
The ancient Roman legion is the greatest military unit the world has ever known. It effectively fought against the “conventional” forces of Greece, Carthage, Parthia, and other Roman legions during the Civil Wars. It fought against “unconventional” forces from Gaul and Britannia, to Judea. It built roads and forts and improved the state of infrastructure wherever it was sent. In all areas, and against all opponents, it was successful. It is no wonder that the Roman legion had so many admirers, especially among the early American officer corps. In a letter exchange, Henry Knox and South American revolutionary Francisco de Miranda called the legion “infinitely superior to any other organization or military arrangement we know yet.”
Maurice de Saxe took the operational concept of the legion and adapted it to the eighteenth century. The legion of ancient Rome predated much of the technology that allowed for combat arms designation. It was an almost entirely heavy infantry unit. Its excellence lie not in its composition, but in its effect. In his writings, Saxe advocated a resurrected legion that achieved the adaptability of its ancient forefather by adopting a combined-arms force structure—a revolutionary concept in its time. Henry Bouquet, a Swiss-born Colonel in the British army, took the idea a step further and wrote that the modular combined-arms force structure was ideal for Indian-fighting in the Americas, i.e. for use against irregulars in unfavorable terrain.
Baron von Steuben wrote a letter in 1784 advocating that the United States adopt a permanent legionary force structure:
Upon a review of all the military of Europe, there does not appear to be a single form which could be safely adopted by the United States; they are unexceptionally different from each other, and like all human institutions, seem to have started as much out of accident as design … The Legion alone has not been adopted by any, and yet I am confident in asserting, that whether it be examined as applicable to all countries, or as it may more immediately apply to the existing or probable necessity of this, it will be found strikingly superior to any other.
Initially ignored upon publication, the letter acquired new meaning after the Massacre at the Wabash. Congress acceded to Washington’s demands and allowed the creation of the Legion of the United States.
President Washington and Secretary Knox abandoned the traditional regimental structure. Instead of a reliance on large regiments of either infantry, cavalry, or artillery, the Legion of the United States was one coherent unit with four self-contained armies making up its constituent parts. The armies, called Sub-Legions, contained 1,280 soldiers each, with two infantry battalions, one rifle battalion, an artillery company, and a cavalry company. The Legion of the United States was meant to address the failures of regimental design while accentuating the benefits of each combat arm. The end result was an adaptable, standardized force of 5,120 men—in no coincidence, exactly the same size as the famed legions of Julius Caesar.
The Battle of Fallen Timbers took place on August 20, 1794. The Legion of the United States proved its excellence by dispersing the opposing army, pacifying the Northwest Territory, and restoring order to the frontier. Its mission accomplished, the Legion was promptly disbanded.
The modular, combined-arms legion is an ideal small wars force structure. The same organizational principles that made the Legion of the United States a success in 1794 apply today. When a conventional power is faced with a number of different potential conflicts, over all scales of intensity and in all types of terrain, the unpredictability of the situation necessitates a standardized, generalist formation like the legion. Especially in an asymmetric scenario of regular versus irregular forces.
The modern Brigade Combat Team (BCT) is the closest the United States Army has ever come to reviving the legionary structure. Semi-combined-arms units of nearly 5,000 soldiers, Brigade Combat Teams come in three varieties: Infantry, Stryker, and Armored. As of 2018, the active U.S. Army has 31. While the advent of BCTs represents a step toward legionary warfare, a true revival of the design and spirit of the Legion of the United States would see the elimination of arms-designation between the BCTs and all echelons of unit organization above them. Small wars are the future of American warfare, and the legion has proven itself the perfect unit organization to overcome every situation such wars present.
 De Miranda, F. (1791, February 2). The Form of the Roman Legion [Letter to Henry Knox]. London.
 De Saxe, M. (1944). Reveries Upon the Art of War. Harrisburg, PA: Military Service Publishing Company.
 Bouquet, H. (1764). Reflections on the War with the Savages of North America.
 Von Steuben, F. (1784). A Letter on the Subject of an Established Militia, and Military Arrangements, Addressed to the Inhabitants of the United States.