During the War of 1812, an invasion of Canada failed due to state militias being widely used, and U.S. troops were unable to stop the British from burning the new capital of Washington, D.C.
However, the Regular Army, under Generals Winfield Scott and Jacob Brown, proved they were professional and capable of winning tactical victories in the Niagara campaign of 1814.
Previously, each colony of British America had relied upon the militia, made up of part-time civilian-soldiers, for local defense, or the raising of temporary "provincial regiments" during specific crises such as the French and Indian War.
On June 15, the Congress elected George Washington as Commander-in-Chief by unanimous vote The enlisted soldiers were young, poor, and often of Irish or German background.
After crossing the Delaware River in the dead of winter, he defeated the British forces in two battles, at Trenton and Princeton, retook New Jersey and restored momentum to the Patriot cause.
Washington submitted his "Sentiments on a Peace Establishment," which called for only a small force of only 2,631 men regiment to guard the western frontier and the borders with Canada and Florida.
Their assignment was to advance to the site of St. Clair's earlier defeat, recover the cannons lost there, and continue to the Miami capital at Kekionga to establish U.S. sovereignty over northern and western Ohio and beyond.
The plans, which were supported by U.S. President George Washington and Henry Knox, Secretary of War, led to the disbandment of the Continental Army and the creation of the Legion of the United States.
The command would be based on the 18th-century military works of Henry Bouquet, a professional Swiss soldier who served as a colonel in the British Army, and French Marshal Maurice de Saxe.
In 1792, Anthony Wayne, a renowned hero of the American Revolutionary War, was encouraged to leave retirement and return to active service as Commander-in-Chief of the Legion with the rank of major general.
Throughout the winter of 1792-3, existing troops along with new recruits were drilled in military skills, tactics, and discipline at Legionville on the banks of the Ohio River near present-day Baden, Pennsylvania.
The overwhelmingly successful campaign was concluded with the decisive victory at Fallen Timbers on August 20, 1794, Major General Anthony Wayne applied the techniques of wilderness operations perfected by Sullivan's 1779 expedition against the Iroquois.
In 1798, during the Quasi-War with France, the U.S. Congress established a three-year "Provisional Army" of 10,000 men, consisting of twelve regiments of infantry and six troops of light dragoons.
An invasion of Canada failed due to the over-reliance of using state militias,[citation needed] and U.S. troops were unable to stop the British Army from burning the new capital of Washington, D.C.
The nation celebrated the Southern militia's great victory under Andrew Jackson, at the Battle of New Orleans in January 1815, after the war had ended with the signing of the Treaty of Ghent on 24 December 1814.
Secretary of War John C. Calhoun reorganized the department into a system of bureaus, whose chiefs held office for life, and a commanding general in the field, although the Congress did not authorize this position.
The embarrassing Union defeat and subsequent inability of the Confederacy to capitalize on their victory resulted in both sides spending more time organizing and training their green armies.
The quartermasters supervised their own soldiers, and cooperated closely with state officials, manufacturers and wholesalers trying to sell directly to the army; and representatives of civilian workers looking for higher pay at government factories.
[24] About 190,000 volunteered, further enhancing the numerical advantage the Union armies enjoyed over the Confederates, who did not dare emulate the equivalent manpower source for fear of fundamentally undermining the legitimacy of slavery.
At Ft. Pillow on April 12, 1864 Confederate units under Maj. Gen. Nathan Bedford Forrest went wild and massacred black soldiers attempting to surrender, which further inflamed passions.
[31][32] According to Louis Cantor, Root designed a dual role for the National Guard - a militia for state service and a trained reserve for the regular army.
Major General Leonard Wood, then Army Chief of Staff, mobilized the division primarily to demonstrate to Congress that the United States was not adequately prepared for modern warfare.
Later, as a further economy move, the War Department reduced the number of command visits to one per year, a restriction that effectively destroyed the possibility of training units as combined arms teams.
The reorganized army doubled in size between the invasion of Poland and the attack on Pearl Harbor, and grew forty-four times between the US entry into the war and the surrender of Japan.
Hundreds of thousands of U.S. troops remained stationed in West Germany, with others in Belgium, the Netherlands and the United Kingdom, until the 1990s in anticipation of a possible Soviet attack.
American forces effectively established and maintained control of the "traditional" battlefield, however they struggled to counter the guerrilla hit and run tactics of the communist Viet Cong and the North Vietnamese Army.
[50] In 1990, Iraq invaded its smaller neighbor, Kuwait, and U.S. land forces, led by the 82nd Airborne Division, quickly deployed to assure the protection of Saudi Arabia.
Within months, the mission changed from conflict between regular forces to counterinsurgency, with large numbers of suicide attacks resulting in the deaths of more than 4,000 U.S. service members (as of March 2008) and injuries to thousands more.
[53] Most of the units that carried out the ground campaign phase of the invasion of Iraq, and who bore the larger part of the conflict with the Iraqi Armed Forces in 2003, were those of the Army.
As a result of this intense operational tempo, deep concerns arose in the U.S. about the effects of frequent combat deployment on the psychological health of US soldiers in Iraq and Afghanistan.