New Definition of a Capital Ship - The capital ships of the Royal Navy have traditionally been the most important warships with the heaviest firepower and armour and are traditionally much larger than other naval vessels.      There is no formal criterion for the classification but the term since 1920 has usually applied to battleships, battlecruisers and aircraft carriers.   In the modern era the Royal Navy's 'capital ship' the Type 23 Frigate WESTMINSTER serving with Combined Task Force 150 in the Middle East, and unusually among ships of this class has a Captain in command, and a detachment of Royal Marines from 43 Commando Fleet Protection Group embarked – and hey presto a modern “Capital Ship” and that’s official.