Navy tactics tend to go in circles. During World War I, some countries that were weak naval powers discovered they could mount torpedoes on motorboats that were so quick and maneuverable that the strong naval powers' battleships couldn't get their guns to bear before the torpedos were launched. They were called torpedo boats. So the great naval powers responded by building small ships with just 100 or so crew and smaller weapons that could be aimed and fired faster. So they were called torpedo boat destroyers. They were send out to escort capital ships as the outer layer of defense, and then there were so useful they got used for lots of little jobs. The torpedo boat destroyers got bigger, to provide more different kinds of weapons on board, larger crews, and more comfortable accommodations so they could stay at sea longer. Then the larger destroyers became vulnerable to motorboat attacks by weak naval powers, such as during the Iran-Iraq War and Gulf War, and the great naval powers responded with small maneuverable launches off the capital ships and destroyers, and the cycle began again.