what is the role of a navy frigate
Frigate In modern navies, frigates are used to protect other warships and merchant-marine ships, especially as anti-submarine warfare (ASW) combatants for amphibious expeditionary forces, underway replenishment groups, and merchant convoys. Ship classes dubbed "frigates" have also more closely resembled corvettes, destroyers, cruisers, and even battleships. Some European navies such as the French, German or Spanish ones use the term "frigate" for both their destroyers and frigates.[citation needed] The rank "frigate captain" derives from the name of this type of ship.
United States Coast Guard In times of war, the Coast Guard or individual components of it can operate as a service of the Department of the Navy. This arrangement has a broad historical basis, as the Coast Guard has been involved in wars as diverse as the War of 1812, the Mexican–American War, and the American Civil War, in which the cutter Harriet Lane fired the first naval shots attempting to relieve besieged Fort Sumter. The last time the Coast Guard operated as a whole within the Navy was in World War II. More often, military and combat units within the Coast Guard will operate under Navy or joint operational control while other Coast Guard units will remain under the Department of Homeland Security.