The 4th Battalion was part of the 12th Indian Infantry Brigade based in Malaya when the Japanese Army invaded in December 1941. The 4/19th Hyderabads were one of the few battalions in Malaya that were relatively well trained in jungle warfare. Although the battalion performed well in the fighting retreat in north-west Malaya, they were practically annihilated at the disastrous Battle of Slim River on 7 January 1942. The few survivors of the 4th Battalion were withdrawn to Singapore where they took part in the brief defence of the island before it surrendered on 15 February 1942.