He volunteered for service in the Second World War; he first saw action during the Battle of France helping to cover the retreat in Flanders before getting to the beaches at Dunkirk. Tilman then served in North Africa, Iraq and Iran before being called on for special duty in 1943. He then was dropped by parachute into Albania behind enemy lines to fight with Albanian and Italian partisans. For his actions there he was awarded the Distinguished Service Order for his efforts, and was given the keys to the city of Belluno which he helped save from occupation and destruction.