The West Point-educated Henry Slocum was made a lieutenant colonel in the 27th New York Volunteer Regiment when the Civil War broke out in April 1861. Severely wounded in the First Battle of Bull Run (Manassas), he recovered in time to lead Union troops in 1862’s Peninsula Campaign and earn a promotion to major general that July. During the decisive Battle of Gettysburg, Slocum led the 12th Corps of the Army of the Potomac, drawing criticism for his hesitation to lead his troops into action on the first day of fighting. Reassigned to the war’s western theater, Slocum later served under General William T. Sherman in the latter’s Atlanta campaign and his famous “March to the Sea,” and went with Sherman to accept the surrender of General Joseph Johnston’s Confederate army in April 1865.
Henry Slocum’s Early Life and Military Career
A native of Onondaga County, New York, Henry Slocum attended the United States Military Academy at West Point, graduating 7th in his class of 43 in 1852. While stationed in Florida during the Seminole Wars and in South Carolina, he studied law in his off-hours. In 1856, he resigned his army commission and set up a law practice in Syracuse.
When the Civil War broke out in April 1861, Slocum resumed his army career and was made a lieutenant colonel in the 27th New York Volunteers. That July, he was severely wounded in the thigh while leading his regiment at the First Battle of Bull Run (Manassas) in Virginia. He received a promotion to brigadier general during his recovery and was given command of a brigade in the Army of the Potomac in October.
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Slocum is Promoted to Major General
Slocum led Union troops in the Peninsula Campaign of 1862, and was promoted to major general on July 4, just days after his distinguished performance on the battlefield at Gaines’ Mill. At the time, he was the second-youngest man in the country (at 34 years old) to hold that rank. He earned more distinction in the Battle of South Mountain that September, but his division was held in reserve during the epic clash at Antietam. After that battle, however, Slocum was given command of an entire corps in recognition of his heroic reputation within the Army of the Potomac.
Slocum’s first battle in command of the 12th Corps took place at Chancellorsville in April 1863. Following the orders of Major General Joseph Hooker, commanding general of the Army of the Potomac, Slocum’s corps waited at Chancellorsville rather than advance into more open ground (as Major General George Meade, commander of the 5th Corps, advised); they fought well but suffered heavy losses in the crushing Union defeat.
Henry Slocum: From Gettysburg to the Carolinas
Days before the Battle of Gettysburg in early July, Hooker stepped aside and Meade assumed command of the Army of the Potomac. During that decisive battle, Slocum commanded the Union’s right wing, and drew criticism for his hesitation to lead his troops into action on the first day of fighting. In the battle’s aftermath, Slocum and the 12th Corps were sent into the war’s western theater to serve under Hooker, whom Slocum greatly mistrusted. Slocum resigned his commission, but President Abraham Lincoln refused to accept his resignation, and instead gave him command of Union forces near Vicksburg, Mississippi.
In mid-1864, General William T. Sherman gave Slocum command of the Union 10th Corps, which took part in Sherman’s Atlanta campaign and were the first soldiers to enter Atlanta after the Confederates evacuated the city in late August. Slocum followed Sherman during the famed March to the Sea and the Carolina campaign, and was with the general when he accepted the surrender of General Joseph Johnston’s Confederate army at war’s end in April 1865.
Henry Slocum’s Post-War Career
After the Civil War, Slocum resigned his army commission and returned to New York. He resumed practicing law in New York City and in 1868 won election to the House of Representatives. He served as a congressman until 1873 and again from 1883 to 1885. He died in Brooklyn, New York, in 1894.