The fighting went on for eight and a half hours. Burnside's IX Corps suffered 3,800 casualties. Lee's army lost about 1,500 who were killed, wounded or missing. But the black troops lost 1,327 men, 450 of whom surrendered. Most of these were murdered by Confederate soldiers as they were marched to the rear under guard. The failure and horror over what happened at the Battle of the Crater caused Burnside to be relieved of his command. He was placed on indefinite leave of absence with no orders to return to duty. This effectively ended his army career. He resigned from the army less than nine months later, on April 15, 1865.