The Royal Navy (RN) is the naval warfare force of the United Kingdom, responsible for defending the country, the Crown Dependencies, and the Overseas Territories from naval attack or invasion. It is a component of His Majesty's Naval Service, and its officers hold their commissions from the King. 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.