Ambrose Everett Burnside (May 23, 1824 – September 13, 1881) was a Union Army general in the American Civil War and a politician from Rhode Island.

Pre Civil War
Burnside graduated from the U.S. Military Academy in 1847 and served in the Mexican-American War and Indian Wars. He resigned in 1852 to manufacture a breech-loading rifle of his own invention; he settled in Rhode Island but failed to gain a government contract and had to assign his patent to creditors. During this period he was also a major general in the state militia. With the outbreak of the Civil War he raised a regiment of which he was appointed colonel.
Civil War
Burnside commanded a brigade at First Bull Run and commanded the North Carolina Expeditionary Corps, which formed the nucleus for the IX Corps. For his successes at Roanoke Island and New Bern he was promoted to major general and offered command of the Army of the Potomac following George McClellan's failure in the Peninsula Campaign. Refusing this, he detached part of his corps to the aid of John Pope in the Second Bull Run Campaign. Again offered command following that debacle, Burnside again declined and was given command of the I and IX Corps during the Maryland operations. He fought at South Mountain and then at the Battle of Antietam, where his two corps were placed on opposite ends of the Union battle line. He nonetheless remained in wing command over the IX Corps—a cumbersome arrangement that may explain his slowness in attacking at “Burnside Bridge”. The delay allowed A.P. Hill's Confederate division to come up from Harpers Ferry and repulse the Union breakthrough.
Fredericksburg
With McClellan's removal after Antietam, Burnside was assigned to command the Army of the Potomac. He reluctantly obeyed this order. On November 14, 1862, President Abraham Lincoln approved General Burnside's plan to capture the Confederate capital at Richmond, Virginia. This plan led to a dramatic Union defeat at the Battle of Fredericksburg on December 13 that year. His advance upon Fredericksburg was rapid, but later delays, due to poor planning in marshalling pontoon bridges for crossing the Rappahannock River, allowed Robert E. Lee to concentrate along Marye's Heights just west of town and easily repulse the Union attacks. Attacks south of town, which were supposed to be the main avenue of attack, were also mismanaged and Union breakthroughs went unsupported. Upset by the failure of his plan, Burnside declared that he himself would lead an assault by his old corps. He was talked out of it, but relations between the commander and his subordinates were strained. Accepting full blame, he resigned from his command as head of the Army of the Potomac; he offered to retire completely from the U.S. Army, but this was refused.
In January, 1863, Burnside launched a second offensive against Lee, but it bogged down in winter rains before it accomplished anything and has been derisively called the Mud March. In its wake he asked that several officers be relieved of duty and court-martialed; he also offered to resign. Lincoln chose the latter option.
1863–1865
Lincoln was unwilling to lose Burnside and assigned him to the Department of the Ohio. Here he dealt with copperheads such as Clement Vallandigham and Confederate raiders such as John Hunt Morgan. In 1863 he advanced to Knoxville, Tennessee, but after the Union defeat at the Battle of Chickamauga, Burnside found the tables turned and he was besieged by James Longstreet in Chattanooga. The siege was raised by troops under William Tecumseh Sherman after Braxton Bragg's defeat at Chattanooga.
Burnside was then ordered to take the IX Corps back to Virginia, where he fought in the Overland Campaign directly under Ulysses S. Grant; he was not assigned initially to the Army of the Potomac because he outranked its commander, Major General George G. Meade. (This cumbersome arrangement was rectified during the Battle of North Anna on May 25, 1864, when his corps was placed under Meade.)
Burnside fought at the Wilderness and Spotsylvania, where he performed in a mediocre manner, appearing reluctant to commit his troops to frontal assaults after the Fredericksburg experience. After North Anna and Cold Harbor he took his place in the siege lines at Petersburg.
In July, 1864, Burnside agreed to a plan suggested by a regiment of Pennsylvania coal miners in his corps: dig a mine under a fort in the Confederate entrenchments and place explosives there. The fort was destroyed and many rebels died in what is known as the Battle of the Crater. But through interference from Meade, Burnside was ordered not to use his division of black troops (specially trained for this mission) and had to use untrained white troops instead. Those troops, badly led by their commanders, entered the crater itself instead of going around the edge, and got caught in the hole, resulting in high casualties. Burnside got the blame for this failure and he was sent on leave and never recalled. He finally resigned his commission on April 15, 1865.
Post Civil War
After his resignation Burnside was employed in numerous railroad and industrial directorships. During the course of his career, he was elected to three one-year terms as governor of Rhode Island (1866–1868). At its inception in 1871, the National Rifle Association chose him as that organization's first president.. During a visit to Europe in 1870 he tried to act as mediator between the French and the Germans in the Franco-Prussian War, 1870–71. In 1874 he was elected a US Senator from Rhode Island and served until his death at Bristol, Rhode Island, on September 13, 1881. He is buried in Swan Point Cemetery, Providence, Rhode Island.
Assessment
Noted for his facial hair, joining his ears to his moustache but with chin clean-shaven; the word burnsides was coined to describe these strips of hair in front of the ears. The syllables were later reversed to give sideburns.
Personally, Burnside was always very unpopular—both in the army and in politics—but he was out of his depth as a senior army commander, a fact no one knew better than Burnside himself. Knowing his capabilities, he twice refused command of the Army of the Potomac until finally being forced under orders to accept it.