At the outbreak of the Second World War, Howell once again offered his services and enlisted in the Australian Army on 14 October 1939. Posted to Eastern Command Headquarters, Paddington, he was granted the rank of staff sergeant, but found staff work to be dull and sought his discharge in February 1941. In August 1944, Howell enlisted in the United States Army for service in the United States Sea Transport Service, and was thus able to participate in the invasion of Leyte at the commencement of the Philippines campaign.