In addition to port security, ship inspection and safety, law enforcement, and search and rescue, the U.S. Coast Guard assumes an important role in national defense at home and abroad. To that end, the Coast Guard has carried out separate and coordinated missions with other armed forces from the Great Lakes to the Atlantic, Pacific, Gulf of Mexico, Mediterranean, Persian Gulf, and polar region. This chronicle of the Coast Guard's contributions to national defense examines participation in World War I, World War II, Korea, the Cold War, Vietnam, and the War on Terror. Among the topics explored are defense threats, drug trafficking, and border security, as well as Coast Guard personnel, training, leadership, and assets. This thorough consideration reveals the Coast Guard's commitment to its heritage and its motto: Semper Paratus (Always Ready).