The Royal Marines have a history stretching back nearly 350 years and encompassing many major battles.
Marines have seen action in a string of conflicts
Able to deploy on ships such as the helicopter carrier HMS Ocean, or the landing ships HMS Bulwark and HMS Albion, or by land, the marines are one of the most called-upon parts of the British armed forces.
Would-be recruits endure gruelling training at the marines' Commando Training Centre at Lympstone in Devon, and on nearby Dartmoor, earning the right to wear the Green Beret.
Training continues for a variety of terrains and climates, in locations including the Middle East, Belize, Borneo and Norway. Some Royal Marines can go on to the elite Special Boat Service.
The Royal Marines have recently been reorganised under the Commando 21 restructuring plan, with most recruits joining 3 Commando Brigade.
There are three commando units in the brigade - 40 Commando at Norton Manor, Somerset; 42 Commando at Bickleigh, Devon and 45 Commando at Arbroath in Angus.
The Amphibious Ready Group is a commando force maintained at sea, typically on HMS Ocean, which can "poise" at a point over the horizon ready to intervene in a conflict.
They can deploy by air, land or sea
The Royal Marines can trace their history back to the 17th Century.
In 1664, the Duke of York and Albany's Maritime Regiment of Foot was founded, with 1,200 troops.
The soldiers were intended to be able to fight on land as well as act as sailors.
During the War of the Spanish Succession in 1704, 1,900 marines joined 400 Dutch counterparts in preventing Spanish reinforcements from reaching Gibraltar, storming the rock and holding it during a nine-month siege.
The Royal Marines' badge carries a reference to Gibraltar to this day.
Operating on sea and land, the Royal Marines fought in the Napoleonic wars, a string of colonial engagements, and in the Gallipoli landings and the Zeebrugge harbour attack in World War I.
During World War II, 80,000 men served in the marines, crewing most of the landing craft at D-Day.
After the war, the marines served in the Malaya Emergency, Borneo, Cyprus, Korea, Suez, and Aden.
In 1982, they played a major role in the Falklands War, "yomping" across much of the island to help capture Port Stanley, and fighting at Goose Green.
The Royal Marines were also deployed in the first Gulf War, Bosnia, Kosovo, Sierra Leone and in 2003 led the amphibious assault on the al-Faw peninsula during the invasion of Iraq.