 Soon after the outbreak of World War II, he re-enlisted in the RAAF, attaining the rank of squadron leader and commanding rescue and communications units in the South West Pacific.Perhaps the oldest operational pilot in the wartime RAAF, Pentland was responsible for rescuing airmen, soldiers and civilians, and earned the Air Force Cross for his "outstanding courage, initiative and skill".He became a trader in New Guinea when the war ended in 1945, and later a coffee planter.