Major General Henry Warner Slocum (USA)
Henry Warner Slocum was born in Delphi, New York. He graduated from the United States Military Academy seventh of 43 cadets in the class of 1852. He tutored his roommate, Philip Sheridan, in mathematics. Slocum was commissioned a second lieutenant in the 1st U.S. Artillery and served in the Seminole War and at Fort Moultrie in Charleston Harbor, South Carolina. He was promoted to first lieutenant in 1855 and resigned his commission in October 1856 to settle in Syracuse, New York. He was admitted to the bar in 1858 and practiced law in Syracuse. He served as the county treasurer and was a member of the New York State Assembly in 1859. He also served as an artillery instructor in the New York Militia with the rank of colonel.
At the outbreak of the Civil War, Slocum was appointed colonel of the 27th New York Infantry. He led the regiment as part of Colonel Andrew Porter’s 1st Brigade, Colonel David Hunter’s 2nd Division at the First Battle of Bull Run on 21 July 1861. The 27th New York suffered 130 casualties and Slocum was severely wounded in the left thigh.
On 9 August 1861, he was promoted to brigadier general of volunteers and commanded the 2nd Brigade of Brig. Gen. William B. Franklin’s 1st Division, Maj. Gen. Irvin McDowell’s I Corps, during the Peninsula Campaign. During the Seven Days Battles, he commanded the 1st Division of Franklin’s VI Corps distinguishing himself at the Battle of Gaines’ Mill on 27 June 1862. V Corps commander Fitz-John Porter complimented Slocum’s division as “one of the best divisions in the Army.”
On 4 July 1862, Slocum was promoted to major general of volunteers, the second youngest man in the Army to achieve that rank. He led his division covering the retreat of Maj. Gen. John Pope after the Second Battle of Bull Run on 29-30 August. At Crampton’s Gap during the Battle of South Mountain on 14 September, Slocum assaulted the enemy line behind a stone wall and routed it. Franklin described the victory as “the completest victory gained up to that time by any part of the Army of the Potomac.”
On 20 October 1862, Slocum was promoted to command of the XII Corps replacing Maj. Gen. Joseph K. Mansfield who was killed at the Battle of Antietam. He led the corps in the Fredericksburg Campaign but was not involved in the fighting at Fredericksburg. At the Battle of Chancellorsville on 1-5 May 1863, Slocum commanded the Union right wing, including the XII Corps, Maj. Gen. George G. Meade’s V Corps, and Maj. Gen. Oliver O. Howard’s XI Corps. Slocum maneuvered his wing into the read of Robert E. Lee’s army, halting the Confederate advance.
Slocum was not considered for command of the Army of the Potomac following Joseph Hooker’s resignation and his junior in rank George G. Meade assumed command. Slocum played a decisive role at Gettysburg. His XII Corps held Culp’s Hill on the Union right ensuring Meade’s ultimate victory against Lee. However, Slocum has been criticized by historians for not immediately coming to Howard’s XI Corps aid on 1 July 1863. Recently uncovered information seems to vindicate Slocum. He immediately sent Brig. Gen. Alpheus S. Williams’ 1st Division to aid Howard at Gettysburg and prepared the rest of his corps to move despite an order from Meade that morning ordering Slocum to “halt [his] command where this order reach[ed] [him].”
When Slocum reached Gettysburg, he outranked Howard and Winfield Scott Hancock and commanded the Union army for about six hours until Meade arrived after midnight. During this time, he formed the Union defensive lines. When Meade asked if the army should attack or await the attack of the enemy, Slocum recommended to “stay and fight it out.”
On 2 July, Meade ordered Slocum to send the entire XII Corps to assist the defense against Lt. Gen. James Longstreet’s assault on the left flank. Slocum wisely held back Brig. Gen. George S. Greene’s brigade on Culp’s Hill. The 1,350-man brigade held out against a massive Confederate assault saving the critical hill for the Union.
After Gettysburg, Howard’s XI Corps and Slocum’s XII Corps under Joseph Hooker were sent to relieve the Army of the Cumberland at Chattanooga, Tennessee. Slocum sent two letters of resignation to President Lincoln when he learned he would be serving under Hooker. A compromise was reached where one division of XII Corps would remain under Slocum’s command to protect the Nashville and Chattanooga Railroad while the other served directly under Hooker.
During the summer of 1864, Slocum commanded the District of Vicksburg and the XVII Corps of the Department of the Tennessee. Slocum’s administration of the district was so efficient and successful that attempts to transfer to a fighting command in Georgia were prevented by Lt. Gen. Ulysses S. Grant.
When Maj. Gen. James B. McPherson was killed during the Atlanta Campaign, command of the Army of the Tennessee opened up. Hooker was passed over and he resigned his commission. John A. Logan and Howard would command the Army of the Tennessee. Maj. Gen. William T. Sherman selected Slocum to command the new XX Corps made up of the remnants of XI and XII Corps. When Atlanta fell, Slocum and his corps were the first to enter the city on 2 September 1864. He was occupation commander for 10 weeks and tried to make the occupation tolerable for the civilians. At the start of the Franklin-Nashville Campaign, Sherman left Slocum with 12,000 troops in Atlanta as Sherman pursued Lt. Gen. John Bell Hood.
During Sherman’s March to Sea, Slocum commanded the newly created Army of Georgia, composed of the Brig. Gen. Jefferson C. Davis’ XIV Corps and Brig. Gen. Alpheus S. Williams’ XX Corps, operating as the left wing. Sherman’s right wing was the Army of the Tennessee commanded by Howard. The men travelled light foraging for supplies on the march to Savannah, Georgia. Slocum took the surrender of the city on 21 December 1864, and then set up fire guards and prevented the city from being damaged. Slocum recommended cutting off Confederate Gen. William J. Hardee’s corps, but Sherman rejected the plan and Hardee escape to fight again at Bentonville.
During the Carolinas Campaign, Slocum’s army was heavily engaged at the Battle of Averasborough on 15-16 March 1865, and the Battle of Bentonville, on 19 March, where Slocum successfully held off a surprise assault by Gen. Joseph E. Johnston. Johnston surrendered on 17 April. Slocum then commanded the Department of the Mississippi from April through September 1865. He resigned and returned to Syracuse, New York.
Slocum ran as the Democratic candidate for Secretary of State of New York in 1865 but was defeated by fellow Gettysburg General Francis C. Barlow. He was elected as a Democrat to the 41st and 42nd Congresses (4 March 1869 – 3 March 1873). Slocum took an active interest in military and veterans’ affairs. He worked in Congress for the exoneration of Maj. Gen. Fitz John Porter who was court-martialed after the Second Battle of Bull Run. Slocum gave a strong speech on Porter’s behalf in Congress on 18 January 1884.
He was appointed Commissioner of the department of city works of Brooklyn, New York in 1876. He was again elected in 1882 as a representative-at-large to the 48th Congress. He remained friends with Sherman until Sherman’s death and both he and Howard planned Sherman’s funeral and were pall bearers along with old foe Joseph E. Johnston. Henry Slocum died on 14 April 1894 in Brooklyn, New York.