Since 1775, in times of national crisis, American merchant mariners have voluntarily rallied to battle enemy ships, submarines, planes, and mines in order to deliver war materials to troops and allies around the world. During World War II, 733 American merchant ships were sunk by enemy action. More than 6795 merchant mariners and 1810 US Navy armed guard personnel were killed or missing from a force of 215,000 merchant mariners and 144,000 US Navy personnel.