Edmund Pendleton Gaines, United States soldier, was born in Culpeper County, Virginia, on March 20, 1777, the son of James and Elizabeth (Strother) Gaines. The family moved to North Carolina at the end of the American Revolution and soon thereafter to Tennessee. After service as a lieutenant in a local militia company, Gaines was commissioned as an ensign in the Sixth United States Infantry (Tennessee) on January 10, 1799. In March of that year he was promoted to second lieutenant; he was honorably discharged on June 15, 1800. He rejoined the army as a second lieutenant in the Fourth United States Infantry on February 16, 1801, and transferred to the Second Infantry in April 1802. He was promoted to first lieutenant that month and to captain on February 28, 1807. During this period he surveyed a road from Nashville to Natchez, served as military collector of Mobile, and commanded the garrison at Fort Stoddert. He was involved in the arrest of Aaron Burr and presented testimony for the prosecution at his trial. Gaines subsequently took an extended leave of absence and began practicing law in Mississippi Territory but returned to the army at the beginning of the War of 1812. On March 24, 1812, he was appointed major of the Eighth Infantry and on July 6, 1812, lieutenant colonel of the Twenty-fourth Infantry. From March 1813 until March 1814 he was colonel of the Twenty-fifth Infantry. His regiment especially distinguished itself at the battle of Chrysler's Field in 1813. He served as adjutant general of the army from September 1, 1813, through March 9, 1814, and at the same time was commander of Fort Erie, Upper Canada. For his successful defense of the post on November 3, 1814, he was promoted to brigadier general. On August 15, 1815, he was brevetted to the rank of major general for his "gallantry and good conduct in defeating the enemy" at Fort Erie, and he received the thanks of Congress and a gold medal "for repelling with great slaughter the attack of the British veteran army superior in numbers" during the American victory at Erie. He was seriously wounded in the fighting and took no further part in the war, but was given command of Military District Number Six, which comprised Louisiana, Mississippi, and Tennessee. He maintained this assignment until May 17, 1815. In 1817 he was sent south to treat with the Creek Indians and when diplomacy failed joined Andrew Jackson's campaign against them and the Seminoles. From 1821 until May 1823 Gaines commanded the Western Department of the United States Army, with headquarters in Louisville, Kentucky, and from December 1823 until December 1825 he commanded the Eastern Department. He was reassigned to the command of the Western Department on December 9, 1825, and served until January 31, 1826. He fought in the Black Hawk War of 1832 and commanded an expedition against the Florida Seminoles, in which he was wounded in the mouth.
Gaines commanded the southwest military division of the United States in 1836. His sympathies were with Texas, although he was prevented by his position from helping with the Texas Revolution. In accordance with neutrality laws, Secretary of War Lewis Cass ordered Gaines to post the Sixth Infantry at Fort Jesup, Louisiana, to prevent armed volunteers from the United States from entering Texas as volunteers for Sam Houston's army. A number of volunteer units crossed the Sabine River at Gaines Ferry, the property of his cousin James Gaines, despite the presence of the army. Gaines's instructions forbade him to cross into Texas unless armed belligerents should threaten to violate United States territorial sovereignty. He was given discretion, however, to cross the Sabine River if Indian depredations should disturb the tranquility of the border. From Fort Jesup, therefore, he detached a regiment of dragoons to the east bank of the Sabine River with the implicit threat to the Cherokees that the tribe's interference with the Texas bid for political independence from Mexico would not be tolerated. He then dispatched Lt. Joseph Bonnell to the Caddo villages of east Texas to persuade them to remain at peace. It was Bonnell who discovered the plot of Manuel Flores to incite the tribes to war against Texas. Gaines further strengthened the frontier by ordering the Sixth United States Infantry to Fort Jesup from Jefferson Barracks. He was absolutely forbidden to join cause directly with the Texas revolutionaries.
Having been falsely informed that 1,500 Indians and 1,000 Mexican cavalrymen were concentrated near Nacogdoches on the Old San Antonio Road, he advanced fourteen of his companies to the Louisiana-Texas frontier and called for a brigade of volunteers each from Louisiana, Arkansas, and Mississippi as well as a battalion from Alabama. After the battle of San Jacinto, Gaines pulled back to Fort Jesup to await developments. Both Stephen F. Austin and Sam Houston urged him to cross the border and establish his headquarters at Nacogdoches. Gaines demurred, but called up an additional requisition of volunteers in the light of a rumored second Mexican invasion of Texas.
As John S. Ford noted in his memoirs, "The presence in Texas of a portion of the regular army of the United States gave rise to many surmises." Francis T. Duffau, for example, a member of John A. Quitman's company of Mississippi volunteers, claimed to have had documentary proof that President Andrew Jackson had assured Sam Houston that if the Mexican army were to cross the Trinity River, Gaines and his army would come to the Texans' aid. Historian Henderson Yoakum wrote that Gaines ordered Col. William Whistler and elements of the Seventh United States Infantry to the Nacogdoches area to suppress Indian hostilities, thus freeing Houston's army to deal with the Mexican invasion.
From June 5, 1837, until December 9, 1839, and from April 2, 1842, to July 12, 1842, Gaines was in command of the Western Division of the United States Army. From July 1842 until February 1843 he was commander of Military Department Number One, with headquarters at New Orleans. At the outbreak of the Mexican War he called upon Louisiana for volunteers for Zachary Taylor's army. Although reprimanded by the War Department for overstepping his authorization in so doing, Gaines nevertheless made similar requisitions on Alabama, Mississippi, and Missouri. He was removed from command for this insubordination and court-martialed at Fortress Monroe, Virginia, but successfully defended himself. From September 1, 1846, until September 7, 1848, Gaines commanded the Eastern Division of the United States Army. He was concurrently commander of Military Department Number Three and Military Department Number Four, effectively the entire eastern United States, from September 1848 until he was relieved from the former command on January 9, 1849, and the latter on December 25, 1848. He held the Western Division command for a final time from January until June 1849.
Gaines was married three times: first to Frances Toulmin; second to Barbara Blount of Tennessee, who died in 1836; and in 1839 to Myra Clark Whitney of New York. General Gaines died of cholera in New Orleans on June 6, 1849.