Pennsylvania-born John Pemberton, an 1837 West Pointer, had a long and adventurous career in the Old Army, serving in Mexico, on the frontier, and with the Utah Expedition. Married into a Virginia family, he elected to fight for the Confederacy in 1861.
From an 1861 assignment to organize Virginia's artillery and cavalry, Pemberton was quickly and unwisely promoted beyond is abilities. In October 1862, he assumed command of the Departments of Mississippi, Tennessee, and East Louisiana. At Vicksburg in 1863 he proved himself no match for Grant. After a short campaign of tactical maneuver and a six-week siege, in which he was both outwitted and outnumbered, Pemberton surrendered the strategic Mississippi River fortress on July, 4 1863.
Southerners unfairly suspected the Northern-born Pemberton of treachery at Vicksburg. Taken captive and later exchanged, he served out the war in a backwater ordnance inspectorate in Virginia.