The next day, 25 November 1950, Walker's Eighth Army was attacked by the Chinese Army and soon the UN forces were in retreat. MacArthur provided the chief of staff, General J. Lawton Collins with a series of nine successive withdrawal lines. On 23 December, Walker was killed when his jeep collided with a truck, and was replaced by Lieutenant General Matthew Ridgway, whom MacArthur had selected in case of such an eventuality. Ridgway noted that MacArthur's "prestige, which had gained an extraordinary luster after Inchon, was badly tarnished. His credibility suffered in the unforeseen outcome of the November offensive ..."