Very Rare subject.  When Wallace completed his term in the South Carolina state legislature, he enlisted as a private in the 18th South Carolina Infantry Regiment.[1][2][5][6] He was soon regimental adjutant[3] and was elected first lieutenant and captain in January 1862.[1][4] In May 1862, he was elected lieutenant colonel.[1][2][4] The regiment was stationed in South Carolina until July 1862.[3][7]When the colonel of the regiment was killed during the Second Bull Run Campaign on August 30, 1862, Wallace succeeded to command of the regiment to rank from that date as colonel.[1][2][3][4] He was not formally nominated for the appointment until June 10, 1864.[2][3]In the brigade of Brigadier General Nathan G. "Shanks" Evans, Wallace commanded his regiment at the Battle of South Mountain and the Battle of Antietam.[1][2][3][4][5] The brigade then went to defend Charleston, South Carolina.[1][2][3][4][5]In the Spring of 1864, the brigade, then commanded by Brigadier General Stephen Elliott, Jr. was ordered to the defense of Petersburg, Virginia.[1][2] The 18th South Carolina Infantry was holding part of the line under which the Union Army explosive charges were detonated which led to the Battle of the Crater on July 30, 1864.[2][4][5] The mine explosion blew up four companies of the 18th South Carolina Infantry and injured Elliott.[2][3][4]William Henry Wallace was promoted to brigadier general, under the Confederate law permitting the Confederate President to appoint twenty temporary brigadier generals on September 20, 1864.[1][2][5] Elliott had been incapacitated by the mine explosion so Wallace commanded his former brigade in Major General Bushrod Johnson's division, IV Corps, until the surrender of the Army of Northern Virginia on April 9, 1865, at Appomattox Court House, Virginia.[1][2][8] Wallace was paroled at Appomattox Court House on that date.[1][2][3]