 The Japanese tried to cut off Burma Corps by sending troops by boat up the Chindwin River to seize the riverside port of Monywa on the night of 1/2 May.The hastily reconstituted 1st Burma Division was unable to recapture Monywa, but allowed the rest of the Corps to withdraw to the north.As the Corps tried to cross to the west bank of the Chindwin by ramshackle ferries to Kalewa, on 10 May the Japanese advancing from Monywa attempted to surround them in a "basin" encircled by cliffs at Shwegyin on the east bank.