Admiralty
It evolved from *Admiralty Navy War Council, (1909–1912) which in turn became the Admiralty War Staff, (1912–1917) before finally becoming the Admiralty Naval Staff in 1917. It was the former senior command, operational planning, policy and strategy department within the British Admiralty. It was established in 1917 and existed until 1964 when the department of the Admiralty was abolished, and the staff departments function continued within the Navy Department of the Ministry of Defence until 1971 when its functions became part of the new Naval Staff, Navy Department of the Ministry of Defence.
Navy
The Spanish "Infantería de Marina" was formed in 1537, making it the oldest, current marine force in the world. The British Royal Marines combine being both a ship-based force and also being specially trained in commando-style operations and tactics, operating in some cases separately from the rest of the Royal Navy. The Royal Marines also have their own special forces unit.