The Royal Navy is the navy of the United Kingdom. It is the oldest part of the British fighting forces. Because it is the oldest, it is called the "Senior Service". From the 18th century until World War II, it was the largest and strongest navy in the world. The Royal Navy was very important in making Britain the superpower of that time. The Naval Service is made up of the Royal Navy, Royal Marines, Royal Fleet Auxiliary, Fleet Air Arm and reserve forces. The Naval Service had 57,000 personnel (people) as of November 2011 including part-time reserve sailors, airmen and marines.