[8] On 9 January 1951, General MacArthur was “directed to defend himself in successive positions, inflicting maximum damage to hostile forces in Korea subject to the primary consideration of the safety of his troops and his basic mission of protecting Japan.” Carl Berger, _The Korea Knot--A Military-Political History_ (Philadelphia: University of Pennsylvania Press, 1957), pp. 131–132, hereafter Berger, _Korea Knot_, quoted with permission of the publisher. Following its evacuation from Hungnam, the 1st Marine Division early in 1951 underwent a brief period of rehabilitation and training in the vicinity of Masan, west of Pusan. From there, the division moved northeast to an area beyond Pohang on the east coast. Under operational control of Eighth Army, the Marines, with the 1st Korean Marine Corps Regiment attached for most of the period, protected 75 miles of a vital supply route from attack by bands of guerrillas. In addition, the Marines conducted patrols to locate, trap, and destroy the enemy. The Pohang guerrilla hunt also provided valuable training for several thousand recently arrived Marine division replacements. In mid-February the 1st Marine Division was assigned to the U.S. IX Corps, then operating in east-central Korea near Wonju. Initially without the KMCs,[9] the Marine division helped push the corps line across the 38th Parallel into North Korea. On 22 April, the Chinese unleashed a gigantic offensive, which again forced UN troops back into South Korea. By the end of the month, however, the Allies had halted the 40-mile-wide enemy spring offensive. [9] The 1st KMC Regiment was again attached to the Marine Division on 17 March 1951 and remained under its operational control for the remainder of the war. CinCPacFlt Interim Evaluation Rpt No. 4, Chap 9, p. 9-53, hereafter _PacFlt EvalRpt_ with number and chapter. Once again, in May, the Marine division was assigned to the U.S. X Corps, east of the IX Corps sector. Shortly thereafter the Communists launched another major offensive. Heavy casualties inflicted by UNC forces slowed this new enemy drive. Marine, Army, and Korean troops not only repelled the Chinese onslaught but immediately launched a counteroffensive, routing the enemy back into North Korea until the rough, mountainous terrain and stiffening resistance conspired to slow the Allied advance.