On December 22 1951 , General Walker was killed in a road accident. Called to replace him was General Mathew Ridgway. Ridgeway, the commander of the 82nd Airborne Division in World War II, was a no-nonsense commander who had a good personal relationship with MacArthur. MacArthur gave Ridgeway unified command of all the forces in Korea; he was also given relative freedom of action. When he arrived in Korea, Ridgway tried to shake up the army, bringing new commanders in. He would have preferred to undertake an offensive, but quickly came to realize that the Army was in no condition to undertake an offensive, and instead needed to rebuild. On New Year's, the Chinese troops began a new offensive. The initial attack was successful, and Allied forces were forced to withdraw. There was not enough room to the north of the Han River to successfully mount a defensive, so Ridgway ordered a withdrawal to the south of the Han River, once again forcing a retreat from Seoul. The withdrawal was orderly, however, and Allied troops were taking 3 Chinese casualties for every loss they incurred. The Allied forces fell back to what was known as the D line, running from the west coast at Pyongtaek to the east coast at Samchok. The UN forces were able to stabilize their lines there.