The main Japanese offensive was launched on the central front in Assam. While a division advanced to Kohima to isolate IV Corps, the main body attempted to surround and destroy IV Corps at Imphal. Since the Japanese attack in Arakan had already failed, battle hardened units were flown from Arakan to aid the besieged forces in Assam. Also, XXXIII Corps was moved from southern India, where they had been training for amphibious operations, to relieve the garrison at Kohima and then push on to relieve Imphal.