Submarine
The First Battle of the Atlantic was the first major battle that was mainly fought between submarines and their enemies. As in later wars, the main jobs of submarines were to enforce a blockade and to sink enemy warships. They usually attacked freighters at night, shooting with their deck guns and then hiding under the water. Sometimes they used their torpedoes, which they could fire while underwater, especially against larger ships and warships. During World War II The US Navy lost around 52 submarines due to combat and non-combat causes.