Royal Navy

The Royal Navy (RN) is the principal naval warfare service branch of the British Armed Forces. Tracing its origins to the 16th century, it is the oldest service branch and is known as the Senior Service. From the end of the 17th century until well into the 20th century it was the most powerful navy in the world, playing a key part in establishing the British Empire as the dominant world power. Due to this historical prominence, it is common – also among non-Britons – to refer to it as "The Royal Navy" without qualification.

Following victory in the First World War the Royal Navy was significantly reduced in size, although at the onset of the Second World War it was still the largest in the world. By the end of the Second World War the United States Navy had emerged as the world's largest. During the course of the Cold War, the Royal Navy transformed into a primarily anti-submarine force, hunting for Soviet submarines, mostly active in the GIUK gap. Following the collapse of the Soviet Union its focus has returned to global expeditionary operations.

The Royal Navy operates a "blue-water" fleet of technologically sophisticated ships including an aircraft carrier (though without fixed-wing aircraft), a helicopter carrier, two landing platform docks, four ballistic missile submarines (which maintain the UK's nuclear deterrent), six nuclear fleet submarines, six guided missile destroyers, 13 frigates, 15 mine-countermeasure vessels and 24 patrol vessels. As of July 2012, there were 78 commissioned ships in the Royal Navy, plus 19 commissioned ships of the Royal Fleet Auxiliary (RFA). The RFA primarily serves to replenish Royal Navy warships at sea, and also augments the Royal Navy's amphibious warfare capabilities through its three Bay-class landing ship dock vessels.

The Royal Navy is part of the Naval Service, which also comprises the Royal Marines, Royal Fleet Auxiliary, Royal Naval Reserve and Royal Marines Reserve. The professional head of the Naval Service is the First Sea Lord, an Admiral and member of the Defence Council of the United Kingdom. The Defence Council delegates management of the Naval Service to the Admiralty Board, chaired by the Secretary of State for Defence. The Royal Navy currently operates three bases in the United Kingdom where commissioned ships are based; Portsmouth, Clyde and Devonport, Plymouth, the latter being the largest operational naval base in Western Europe.