Just before the start of the Civil War, Torbert was appointed a first lieutenant in the Confederate States Army on March 16, 1861, but he refused the appointment and remained a lieutenant in the U.S. Army.
By September 16, he was appointed colonel of the 1st New Jersey Infantry and, by August 29, 1862, he was a brigade commander in the VI Corps of the Army of the Potomac. In the Maryland Campaign of 1862, he was wounded at Crampton’s Gap in the Battle of South Mountain. He was promoted to brigadier general on November 29, 1862. Torbert commanded his New Jersey brigade in the campaigns leading to the Battle of Fredericksburg, the Battle of Chancellorsville, and the Battle of Gettysburg.
On April 10, 1864, Torbert was given command the 1st Division of the Cavalry Corps of the Army of the Potomac, following the death of Maj. Gen. John Buford. Torbert commanded during the Overland Campaign, except when ill following the Battle of Spotsylvania Courthouse. Brig. Gen. Wesley Merritt commanded in his place for a time. During Maj. Gen. Philip Sheridan’s Valley Campaigns of 1864, Torbert commanded the Cavalry Corps of the Army of the Shenandoah and was promoted to brevet major general on September 9, 1864. Sheridan was unhappy with the performance of the cavalry at the time of the Battle of Fisher’s Hill. He is said to have told Torbert to go out and “whip or be whipped.” The result was a defeat for the Confederate cavalry in the Battle of Tom’s Brook.
Torbert commanded the vestigial Army of the Shenandoah from April 22 to June 27, 1865. Merritt commanded Torbert’s former corps under Sheridan in the last campaigns of the Civil War in Virginia. Torbert received brevet promotions in the regular army for his service at Gettysburg, Haw’s Shop, Third Winchester, and Cedar Creek.