James H. Wilson

After the start of the Civil War, Wilson received promotions to second and first lieutenant and became the topographical engineer for the Port Royal Expeditionary Force, from September 1861 to March 1862. As the topographical engineer for the Department of the South, he took part in the Battle of Fort Pulaski at the mouth of the Savannah River and received a brevet promotion to major in the regular army for his service. He transferred to the Army of the Potomac in April 1862 and served as its topographic engineer, but also as an aide-de-camp to Maj. Gen. George B. McClellan. He served under McClellan during the Maryland Campaign and was present at the battles of South Mountain and Antietam.

Wilson was transferred to the Western Theater and joined Maj. Gen. Ulysses S. Grant's Army of the Tennessee as a lieutenant colonel and topographical engineer. During the Vicksburg Campaign, he was the inspector general of Grant's army. On October 30, 1863, he was promoted to brigadier general of volunteers. He continued on staff duty during the Battle of Chattanooga and was chief engineer of the force sent to relieve Knoxville under Maj. Gen. William T. Sherman.

In 1864, Wilson switched from engineering to the cavalry. On February 17, 1864, he was assigned as chief of the Cavalry Bureau in Washington, D.C. He was an excellent administrator and organizer, but his true talents turned out to be as a combat leader. Grant promoted him to brevet major general on May 6, 1864, and had him assigned to command a division of cavalry under Maj. Gen. Philip Sheridan, which he did with boldness and skill in numerous fights of the Overland Campaign and in the Valley Campaigns of 1864.

General Wilson's ill-fated joint adventure with General Brigadier General August V. Kautz was launched through General Grant's strategy of interdicting Robert E. Lee's supply lines to Petersburg, Virginia. If this could be done, Lee would be compelled to abandon Petersburg. General Wilson was ordered to conduct a cavalry raid that would destroy the tracks of the South Side and Richmond & Danville railroads, and to destroy the key R&D railroad bridge over the Staunton River. The raid began on June 22, 1864, with over 5,000 Cavalry troops and 16 pieces of artillery. During the first three days of their raid, Wilson's cavalry tore up 60 miles of track and burned two trains and several railroad stations. Confederate General W. H. F. "Rooney" Lee pursued the Union raid, but was ineffective. The audacious raid seemed to be wildly successful, though not uncontested, and the Staunton River Bridge loomed as the great objective. The railroad bridge was over a small but deep river, the Staunton. The Confederacy had sensed its strategic importance, putting a small fort there under Captain Benjamin Farinholt, and his 296 reserve troops. A valiant stand by local volunteers of old men and boys, with help from surrounding counties, gathered almost a force of nearly 1,000, which halted the 5,000 well-armed troops. Wilson’s cavalry fought the action dismounted. "Rooney" Lee's cavalry came up during the engagement's end, and routed Wilson's troops. There has been speculation that this damaged an otherwise brilliant career for Wilson.

However, just before Sheridan's decisive Battle of Cedar Creek in October 1864, Wilson was upgraded to brevet major general of volunteers and transferred back to the West to become chief of cavalry for the Military Division of the Mississippi under Sherman.

As cavalry chief, he trained Sherman's cavalry (under Brig. Gen. Judson Kilpatrick) for the March to the Sea. Rather than accompanying Sherman, however, he and 17,000 troopers were attached to Maj. Gen. George H. Thomas's Army of the Cumberland for the Franklin-Nashville Campaign in November and December 1864. His repulse of a flanking attack by Maj. Gen. Nathan Bedford Forrest was instrumental in saving the Union Army at the Battle of Franklin; Wilson was one of only a few Union officers to best the legendary Southern cavalryman. He was promoted to brevet brigadier general in the regular army for his service in the Battle of Nashville. He led the successful Wilson's Raid through Alabama and Georgia, defeating the smaller force of Forrest and capturing Selma, Alabama, along with four other fortified cities. In this campaign, he commanded the troops that burned most of the buildings of the University of Alabama. On Easter Day, 1865, his troops assaulted and captured the city of Columbus, Georgia. His men did enormous damage to the military infrastructure of the South, but they did it with a sense of discipline that usually prevented looting and other collateral damage to civilian property. He was promoted to brevet major general in the regular army for his performance at Selma and received his full promotion to major general on May 6, 1865. In central Georgia, the cavalrymen under Wilson's command captured Confederate President Jefferson Davis, and Captain Henry Wirz, the commandant of Andersonville, as he fled through Georgia in May 1865. Wilson's administration of post-war Georgia was regarded, in some cases, as enlightened. In his History of the State of Georgia from 1850 to 1881, the historian I.W. Avery remarks:

In many particulars the Federal soldiers acted very cleverly. Gen. [James H.] Wilson turned over to Gen. Ira Foster the Confederate mules, horses, wagons, and harness, for distribution to the poor, and Col. J.H.R Washington of Macon, was associated with Gen. Foster to aid in the distribution.

On June 24, 1865, in General Order #31, General Wilson expressed appreciation to Foster and Washington, and relieved them of their authority, placing the task with Capt. R. Carter, A.Q.M., Cavalry Corps Military Division of the Mississippi.

At the end of the war, Wilson reverted to the rank of lieutenant colonel and was assigned to the newly created 35th U.S. Infantry, but his duty assignments continued to be in the Corps of Engineers until he resigned from the Army in December 1870.