James Harrison Wilson was born in Shawneetown, Illinois. In 1860, he graduated from the United States Military Academy and became a brevet second lieutenant in the Topographical Engineers in the Department of Oregon at Fort Vancouver. During the Civil War, Wilson served as a topographical engineer, and in 1863 he was promoted to become Ulysses Grant's brigadier general of volunteers. In 1864, he switched from engineering to the cavalry, was promoted to brevet major general, and commanded a division of cavalry before becoming chief of cavalry for the Military Division of the Mississippi under Sherman. He trained Sherman's cavalry, then led the raids through Alabama and Georgia. In 1865, he was promoted major general. At the end of the war, Wilson served in the Corps of Engineers until 1870, when he retired from the Army. He worked as a railroad construction engineer and executive. In 1883, he moved to Wilmington, Delaware, and worked, traveled, and wrote. In 1898, the Spanish-American war began, and Wilson returned to the Army. He served as a major general in Cuba and Puerto Rico, and was in China during the Boxer Rebellion in 1901. In 1902 he retired from the Army.