The world's merchant shipping fleet comprises some 27,000 ships (752 million deadweight tons.) Any future war would require massive amounts of supplies to be moved by sea to the combat zone. World War II was noted for the crucial role merchant shipping played in the conflict. Each Allied soldier required about ten tons of supplies a year to keep fighting. Most of the supplies came from North America and they had to be moved in merchant ships. German submarines sank 21 million (deadweight) tons of Allied shipping (5,000 vessels) during the war. But America was able to built 19 million tons of shipping in 1943 alone. Today, each soldier requires close to a hundred tons of supplies a year to stay in action. Today's merchant ships are larger, and nuclear subs are even more formidable. But unlike World War II, where the U.S. navy was but one of several large navies, today the American fleet comprises over half the naval combat capability in the world. There may never be another "Battle of the Atlantic" as there was from 1939-45, but if there is, it will be on a far larger scale.