The British were in full retreat from northern Malaya. Two battered Indian brigades were arranged in depth back through Trolak to the Slim River bridge. In the early morning hours of 7 January, a Japanese tank company accompanied by truck-borne infantry charged down the road. The Japanese tanks quickly overran the bulk of the 12th Brigade, and next up for lighting-fast defeat was the 28th Brigade. Because of very poor British communications, the brigade were unaware of the impending threat, and the Japanese caught them on the move.