American Civil War: Major General Henry Slocum

Henry Slocum
Major General Henry Slocum. Photograph Courtesy of the Library of Congress

Henry Slocum - Early Life & Career:

The son of an educator, Henry Warner Slocum was born at Delphi, NY on September 24, 1827. Educated at nearby Cazenovia Seminary, he, like his future comrade in the Army of the Potomac John Sedgwick, initially began a career in teaching before electing to attend West Point. Obtaining an appointment to the US Military Academy in 1848, Slocum roomed with Philip Sheridan.

An above average student, he graduated in 1852 ranked seventh in a class of forty-three. Commissioned as a second lieutenant in the 1st US Artillery, Slocum saw service in Florida against the Seminoles before receiving orders for Fort Moultrie in Charleston, SC. Frequently bored with garrison life, he began studying law in his free time and in 1854 married Clara Rice. Finishing his studies, Slocum elected to resign from the US Army on October 31, 1856.

Henry Slocum - the Civil War Begins:

Returning to Syracuse, NY, Slocum commenced practicing law. Increasingly successful, he won office as county treasurer and in 1859 was elected to the New York State Assembly. Though Slocum had departed the US Army, he remained active in military matters and served as a colonel in the New York State Militia. In this role, he worked as an artillery instructor. With the beginning of the Civil War in April 1861, Slocum was appointed colonel of the 27th New York State Infantry.

Arriving in Washington, DC, the regiment was assigned to Colonel Andrew Porter's brigade in Brigadier General David Hunter's division. On July 21, Slocum's regiment took part in the First Battle of Bull Run. Heavily engaged near Henry House Hill, the 27th New York sustained around 130 casualties and Slocum was wounded in the thigh.

Recovering from his wound, he received a promotion to brigadier general on August 9, 1861.

Henry Slocum - A Rapid Rise:

In October, Slocum took command of a brigade in Brigadier General William Franklin's division of the Union I Corps. While Franklin's division initially saw duty along the Potomac, it was transferred south in May 1862 to take part in Major General George B. McClellan's Peninsula Campaign. Arriving, the division joined with other Union formations to create VI Corps. As part of this reorganization, Franklin assumed command of the corps while Slocum ascended to lead the division. Slowly pressing up the Peninsula, McClellan's advance was stopped at the Battle of Seven Pines in late May. The following month, the new Confederate commander, General Robert E. Lee, commenced a counter-offensive with the goal of pushing Union forces away from Richmond. Dubbed the Seven Days Battles, it saw Confederate forces attack the Brigadier General Fitz John Porter's V Corps on July 27 at the Battle of Gaines' Mill. During the course of the fighting, Slocum's division arrived and reinforced Porter's line. Despite their efforts, the combined Union force was overwhelmed and forced to retreat late in the day.

Slocum returned to action three days later when his command took part in the Battle of Glendale. For his actions on the Peninsula, Slocum received a promotion to major general on July 25. A deliberate and thoughtful officer, at age thirty-four he became one of the youngest men to achieve that rank. With the failure of McClellan's campaign, VI Corps moved north to support Major General John Pope's campaign in Northern Virginia. In the wake of Pope's defeat at Second Manassas in late August, Slocum's men advanced and helped and cover the Union retreat. Having routed Pope, Lee moved north to invade Maryland. Pursuing, McClellan attacked Confederate forces at the Battle of South Mountain on September 14. Fighting near Crampton's Gap, Slocum goaded the slow Franklin into mounting an attack late in the day which ultimately carried the heights.

Henry Slocum - XII Corps:

Three days later, the two armies clashed at the Battle of Antietam. Though present, Slocum did not take part in the fighting as McClellan retained VI Corps as a reserve. On October 20, he assumed command of XII Corps as its former leader, Major General Joseph K. Mansfield, had been killed in the fighting. For most of the next month, XII Corps remained in the area of Harpers Ferry while the new commander of the Army of the Potomac, Major General Ambrose Burnside, began moving troops south towards Fredericksburg. Though Slocum received orders to bring his men to join the army's reserve on December 9, he did not arrive prior to Burnside's defeat at the Battle of Fredericksburg. The loss led to Burnside being replaced by Major General Joseph Hooker in early 1863.

In late April 1863, Hooker commenced a plan for moving the bulk of his army west with the goal of getting in Lee's rear. Assigned command of the army's right wing, consisting of V, XI, and XII Corps, Slocum began moving west and crossed the Rappahannock River. Later joined by Hooker with II and III Corps, Slocum advanced east towards the enemy. Meeting the Confederates on May 1, the Battle of Chancellorsville began. The next few days saw XII Corps take part in heavy fighting as Hooker was beaten and forced to retreat north of the river. Following the battle, Lee began moving north with the intention of invading Pennsylvania. As the Army of the Potomac followed, Hooker was replaced by Major General George G. Meade.

Henry Slocum - "Slow Come":

On July 1, the Battle of Gettysburg opened when Confederate forces attacked Union cavalry led by Brigadier General John Buford. The fighting soon grew as Major General John Reynolds' I Corps and Major General Oliver O. Howard's XI Corps arrived on the scene. Moving up the Baltimore Pike, XII Corps halted at Two Taverns, approximately five miles southeast of Gettysburg around mid-morning. Early that afternoon, Slocum received a message from Howard calling for immediate assistance. Hesitating, he did not begin advancing until late in the afternoon despite the fact that he would have been the senior general on the field. Slocum later argued that he was not aware of the fighting due to an acoustical shadow caused by the local hills. His actions on July 1 earned him the nickname "Slow Come" and it was not until 6:00 PM that XII Corps arrived in Gettysburg.

Over the next two days, Slocum led the "right wing" of Meade's army and delegated operational control of XII Corps to Brigadier General Alpheus S. Williams. On the afternoon of July 2, he resisted Meade's orders to send all of XII Corps south to reinforce the Union left and succeeded in retaining Brigadier General George S. Greene's brigade on Culp's Hill. This proved providential as Greene later turned back several Confederate assaults on the heights. Returning to Culp's Hill, XII Corps defeated several enemy assaults on the morning of July 3. Following the Confederate defeat, Slocum and his corps took part in the pursuit of Lee back to Virginia.

Encamped near the Rappahannock, XI and XII Corps were detached from the army on September 23 and ordered west to join Major General William S. Rosecrans's Army of the Cumberland which was besieged in Chattanooga following their defeat at Chickamauga.

Henry Slocum - In the West:

Shifting to Tennessee, Slocum learned that the combined XI and XII Corps force was to be led by Hooker. As he had frequently clashed with Hooker during the Chancellorsville Campaign and had lobbied for his removal after the battle, Slocum offered his resignation rather than serve under his former commander. Not wishing to lose Slocum, President Abraham Lincoln refused the resignation and saw that a compromise was found. This resulted in Slocum taking one of XII Corps' divisions to guard the Nashville & Chattanooga Railroad while Hooker took the other and XI Corps to take part in Major General Ulysses S. Grant's efforts relieve Chattanooga. This arrangement functioned in the short term and in 1864 Slocum was appointed to command Union forces at Vicksburg. In July, Major General James B. McPherson, commander of the Army of the Tennessee, was killed at the Battle of Atlanta.

In seeking a new commander for the army, Major General William T. Sherman selected Howard over Hooker. Outraged, Hooker resigned and left Sherman's command. On August 27, Slocum was offered Hooker's former post overseeing XX Corps, which had been created by combining XI and XII Corps. Leading XX Corps for the remainder of the Atlanta Campaign, Slocum and his men received the city's surrender on September 2. Briefly commanding Atlanta that fall, Slocum received command of the newly-formed Army of Georgia in November. Consisting of XX and XIV Corps, this new formation served as the left wing of Sherman's March to the Sea. Moving southeast, the Army of George lived off the land and pushed though light opposition before reaching Savannah on December 10.

Henry Slocum - The Carolinas:

With Lieutenant General William Hardee holding the city with around 10,000 men, Slocum advocated for destroying the causeways from the Savannah in an effort to trap the garrison. Sherman elected not to take action and Hardee escaped across the Savannah River on December 20. After taking the city, Sherman reinforced and embarked on his Carolinas Campaign in January 1865. Driving through South Carolina, Slocum's men reached Columbia in mid-February. Continuing on, Sherman's armies entered North Carolina and fought Hardee at Averasborough on March 16. Moving towards Goldsboro, Slocum was attacked by General Joseph E. Johnston at Bentonville three days later. Though he initially thought he was only facing cavalry, he soon came to recognize the size of the Confederate opposition and formed a defensive line. After requesting aid from Sherman, Slocum's men turned back several Confederate assaults through the afternoon

Reinforced by Howard on March 20, Slocum turned the battle over to Sherman. Recognizing the threat posed by the combined Union force, Johnston retreated on the night of March 21. Pressing north, Sherman ended the campaign on April 26 when Johnston surrendered at Bennett Place near Durham, NC. With the end of the war, Slocum commanded the Department of the Mississippi before resigning from the army on September 28. Returning home, he mounted an unsuccessful campaign for Secretary of State of New York.

Henry Slocum - Later Life:

In the years after the war, Slocum resumed his law practice and declined a commission as a colonel in the US Army. A Democrat, he was elected to Congress in 1868 and served until 1873. While in office, Slocum worked to exonerate Porter who had been court-martialed for his role in the defeat at Second Manassas. In 1876, he accepted the post of President of the Department of City Works for Brooklyn, NY. As president, Slocum played a key role in the construction of the Brooklyn Bridge which opened in 1883. That same year, he returned to Congress for one term. A member of the Board of Gettysburg Monuments Commissioners, Slocum died at Brooklyn, NY on April 14, 1894 and was buried in the city's Green-Wood Cemetery.

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