The Corps of Royal Marines (RM) is an amphibious light infantry and also one of the five fighting arms of the Royal Navy. The marines can trace their origins back to the formation of the English Army's "Duke of York and Albany's maritime regiment of Foot" at the grounds of the Honourable Artillery Company on 28 October 1664.As a highly specialised and adaptable elite light infantry force, the Royal Marines are trained for rapid deployment worldwide and capable of dealing with a wide range of threats. The Royal Marines are organised into a light infantry brigade (3 Commando Brigade) and a number of separate units, including 47 Commando (Raiding Group) Royal Marines, and a company strength commitment to the Special Forces Support Group. The Corps operates in all environments and climates, though particular expertise and training is spent on amphibious warfare, arctic warfare, mountain warfare, expeditionary warfare, and its commitment to the UK's Rapid Reaction Forces.

Throughout its history, the Royal Marines have seen action in a number of major wars often fighting beside the British Army – including the Seven Years' War, the Napoleonic Wars, the Crimean War, World War I and World War II. In recent times the Corps has been largely deployed in expeditionary warfare roles such as the Falklands War, the Gulf War, the Bosnian War, the Kosovo War, the Sierra Leone Civil War, the Iraq War and the War in Afghanistan. The Royal Marines have close international ties with allied marine forces, particularly the United States Marine Corps and the Netherlands Marine Corps (Dutch: Korps Mariniers). Today, the Royal Marines are an elite fighting force within the British Armed Forces, having undergone many substantial changes over time.