Although warships were used by English and Scottish kings from the early medieval period, the first major maritime engagements were fought in the Hundred Years' War against France. The modern Royal Navy traces its origins to the English Navy of the early 16th century; the oldest of the UK's armed services , it is consequently known as the Senior Service.
From the 19th century until the Second World War , it was the world's most powerful navy. The Royal Navy played a key part in establishing and defending the British Empire , and four Imperial fortress colonies and a string of imperial bases and coaling stations secured the Royal Navy's ability to assert naval superiority. Following World War I , it was significantly reduced in size.
Following the collapse of the Soviet Union , its focus returned to expeditionary operations. The Royal Navy maintains a fleet of technologically sophisticated ships, submarines, and aircraft, including 2 aircraft carriers , 4 ballistic missile submarines which maintain the nuclear deterrent , 5 nuclear fleet submarines , 6 guided missile destroyers , 8 frigates , 7 mine-countermeasure vessels and 26 patrol vessels. There are also four Point-class sealift ships from the Merchant Navy available to the RFA under a private finance initiative , while the civilian Marine Services operate auxiliary vessels which further support the Royal Navy in various capacities.
The RFA replenishes Royal Navy warships at sea and, as of , provides the lead elements of the Royal Navy's amphibious warfare capabilities through its three Bay-class landing ship vessels. It also works as a force multiplier for the Royal Navy, often doing patrols that frigates used to do. The Royal Navy stated its six major roles in umbrella terms in as.
The Royal Navy protects British interests at home and abroad, executing the foreign and defence policies of His Majesty's Government through the exercise of military effect, diplomatic activities and other activities in support of these objectives. During much of the medieval period, fleets or "king's ships" were often established or gathered for specific campaigns or actions, and these would disperse afterwards. These were generally merchant ships enlisted into service.
