The story of the Battle of the Atlantic is well known, but the Indian Ocean submarine war is much less noted despite the fact that men and submarines of every major combatant nation were engaged. Submarines of seven nations fought a war of attrition from 1939 to 1945. The Indian Ocean had important trade routes from India to Africa, and the Mediterranean for the Allies and was part of the trade route between Japan and Germany. It was an important battlefield but little has been written about it.