Ambrose Burnside was born on May 23, 1824 in Liberty, Indiana. After finishing primary school, he enrolled at the United States Military Academy in West Point in 1847. After graduating, he was commissioned as a Second Lieutenant in the 2nd Artillery.

At this time, the United States was at war with Mexico and Burnside's unit was sent to the front lines. Burnside served under Braxton Bragg for most of the war and helped to seize Mexico City. At the end of the war, he was sent to fight the Apache Indians in New Mexico, who were resisting settlement by whites.

He fought the Apaches in the southwest with the US Army for over two years. In 1849, an arrow struck him in the neck, wounding him, but he was able to recover from the injury. In 1852, he was transferred to Fort Adams in Rhode Island, where he was given command of the fort.

While serving in Rhode Island, Ambrose met a woman named Mary Bishop and decided to marry her. In 1853, he resigned from the US Army, but retained membership in Rhode Island's militia. He decided to start a firearms company and named it the Burnside Arms Company. As head of the company, he designed their flagship product, the Burnside Breechloading Carbine.

The Secretary of War at the time, John Floyd, was impressed with the rifle and signed a contract to have the company supply the military with it. However, after Burnside had built some new factories to meet the new demand, Floyd was bribed by a competitor and dropped the contract. Burnside lost a tremendous amount of money from the withdrawal and he was financially ruined.

A totally destitute Burnside began to seek employment and decided to work for the Illinois Central Railroad as its treasurer. There, he met George McClellan, a man who he would later serve under in the Civil War. In 1858, Burnside ran for one of Rhode Island's seats in the US House of Representatives, but was defeated by a wide margin.

When the Civil War began, Burnside helped to organize a regiment in Rhode Island. He was appointed its commander with the rank of Colonel on May 2, 1861. After a month, he was placed in command of a brigade and participated in the First Battle of Bull Run. On August 6, 1861, he was appointed Brigadier General and given command of the North Carolina Expeditionary Corps.

After successful battles in Roanoke Island and New Bern, Burnside was promoted to the rank of Major General on March 18, 1862. He was then ordered to move to northern Virginia to form the 9th Corps of the Army of the Potomac under George McClellan. After McClellan's utter failure in the Peninsula Campaign, Burnside was offered command of the Army of the Potomac, but declined due to lack of experience. He was offered again after the Second Battle of Bull Run, but declined again.

During the Maryland Campaign, Burnside commanded the 1st and 9th Corps of the Army of the Potomac. He fought at the Battle of South Mountain as well as the Battle of Antietam during the Campaign. At Antietam, his two Corps were placed on opposing ends of the Union line, making it rather difficult for him to command them.

After the Battle of Antietam, McClellan was fired and Burnside finally agreed to take his position on November 7, 1862 after being ordered to do so. Burnside decided to move into Virginia to seize Richmond, but met a disastrous defeat while attacking the city of Fredericksburg. The entire battle was poorly managed, with many delays in getting across the Rappahannock River and advancing before Lee was able to reinforce his lines. After numerous failed frontal assaults, Burnside declared that he would lead the 9th Corps into battle himself, but he was talked out of the idea by his subordinates.

Following the battle, Burnside offered to resign, but Lincoln refused to let him do so. In January of 1863, Burnside pursued Robert E. Lee's forces near Fredericksburg, but was slowed tremendously by heavy rains. The roads turned to deep mud, causing wagons to get stuck and forcing troops to walk in mud up to their knees. After two days, Burnside ordered his troops back to Fredericksburg, ending the so-called "Mud March".

Following the Mud March, Burnside again offered to resign and Lincoln accepted his resignation on January 26, 1863. Lincoln reassigned Burnside to command the Department of the Ohio, where he mainly fought small bands of Confederate raiders. He advanced his 9th Corps to the city of Knoxville, Tennessee, but was attacked by Longstreet's forces.

After Longstreet retreated, Burnside was ordered to move his troops to Virginia and participated in the Overland Campaign under Ulysses S. Grant. Since Burnside outranked the commander of the Army of the Potomac, George Meade, he did not initially combine forces. However, he decided to allow Meade to directly command him and joined the Army of the Potomac for the Battle of North Anna on May 25, 1864.

In July of 1864, Burnside accepted a regiment of coal miners from Pennsylvania into his 9th Corps. The plan was to dig a mine underneath a Confederate fort on the front lines at Petersburg and ignite a large quantity of explosives to blow up the fort and any nearby Confederate forces. The mine was dug by the coal miners and completed on July 17th of 1864. On July 30, 1864, the fuse was lit, and the charges exploded, killing somewhere around 300 Confederate soldiers.

After the explosion, a division of Burnside's 9th Corps was ordered to secure the blast crater. The troops were inexperienced and made the mistake of entering the crater, only to be attacked by Confederates above and suffer tremendous losses. The operation became known as the Battle of the Crater.

Burnside was blamed fully for the failure and left the Army on leave. He officially resigned on April 15, 1865 and went back into the railroad business. He served as president of The Cincinnati Railroad and several other companies, including the Rhode Locomotive Works. He ran for governor of Rhode Island in 1866, and was elected to serve until 1868.

In 1870, Burnside made a diplomatic trip to Europe, where he attempted to help France and Germany settle their differences during the Franco-Prussian War. In 1871, when the National Rifle Association was started, Burnside was appointed as its first president. In 1874, he was elected as a Senator for Rhode Island and served for seven years.

Ambrose Burnside died on September 13, 1881 of natural causes. He was buried in the Swan Point Cemetery in Providence, Rhode Island. After his death, his facial hair style became popularized and received its namesake "sideburns" from him.