XX Corps (Union Army)

XX Corps
XX Corps badge
Active	1863–1865
Type	Army Corps
Size	Corps
Part of	Army of the Cumberland
Engagements	American Civil War
Commanders
Notable commanders	Joseph Hooker Henry W. Slocum Alpheus S. Williams
Insignia
1st Division
2nd Division
3rd Division

Two corps of the Union Army were called XX Corps during the American Civil War. Though both served in the Union Army of the Cumberland, they were distinct units and should be recognized as such.

The first XX Corps, under the command of Alexander M. McCook, was organized in the aftermath of the Battle of Stones River in January 1863 from what had been the XIV Corps, or right wing of the army, at that battle. It was so identified with its commander that it was generally referred to by other soldiers and even officers as "McCook's corps".

The corps took part in a skirmish with Bragg's rearguard at Liberty Gap, Tennessee, during the Tullahoma Campaign in June 1863. It fought its only major battle under this designation at Chickamauga, where it suffered horrendous casualties in the two days of fighting. The corps took heavy casualties, and it (along with Thomas L. Crittenden's XXI Corps), became consolidated into the new IV Corps. McCook, blamed in large part for the failure at Chickamauga, was relieved of command.

After the Battle of Gettysburg, with the armies of the east engaged in stalemate (and a large portion of Robert E. Lee's Army of Northern Virginia, under James Longstreet, was serving with Braxton Bragg in Tennessee), Washington dispatched Joseph Hooker, discredited after his defeat at the Battle of Chancellorsville the previous May, with the XI and XII Corps of the Army of the Potomac to try to relieve Bragg's siege of Chattanooga. The command played a decisive role in the Battle of Wauhatchie, which opened up the "Cracker Line" to the besieged Union army, and seized Lookout Mountain in the famed "Battle Above The Clouds" during the early stages of the Battle of Chattanooga.

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Wikipedia