at Dartmouth, Devon. Personnel are divided into a warfare branch, which includes Warfare Officers (previously named seamen officers) and Naval Aviators, as well other branches including the Royal Naval Engineers, Royal Navy Medical Branch, and Logistics Officers (previously named Supply Officers). Present-day officers and ratings have several different uniforms; some are designed to be worn aboard ship, others ashore or in ceremonial duties. Women began to join the Royal Navy in 1917 with the formation of the Women's Royal Naval Service (WRNS), which was disbanded after the end of the First World War in 1919. It was revived in 1939, and the WRNS continued until disbandment in 1993, as a result of the decision to fully integrate women into the structures of the Royal Navy. Women now serve in all sections of the Royal Navy including the Royal Marines. In August 2019, the Ministry of Defence published figures showing that the Royal Navy and Royal Marines had 29,090 full-time trained personnel compared with a target of 30,600. In December 2019 the First Sea Lord, Admiral Tony Radakin, outlined a proposal to reduce the number of Rear-Admirals at Navy Command by five. The fighting arms (excluding Commandant General Royal Marines) would be reduced to Commodore (1-star) rank and the surface flotillas would be combined. Training would be concentrated under the Fleet Commander. Surface fleet Aircraft carriers The Royal Navy has two s. Each carrier costs £3 billion and displaces . The first, , commenced flight trials in 2018. Both are intended to operate the STOVL variant of the F-35 Lightning II. Queen Elizabeth began sea trials in June 2017, was commissioned later that year, and entered service in 2020, while the second, , began sea trials on 22 September 2019, was commissioned in December 2019 and was declared operational as of October 2021. The aircraft carriers will form a central part of the UK Carrier Strike Group alongside escorts and support ships. Amphibious warfare Amphibious warfare ships in current service include two landing platform docks ( and ). While their primary role is to conduct amphibious warfare, they have also been deployed for humanitarian aid missions. Clearance diving The Royal Navy clearance diving unit, the Fleet Diving Squadron, was reorganised and rebranded to the Diving and Threat Exploitation Group in 2022. The group consists of five squadrons: Alpha, Bravo, Charlie, Delta, and Echo. The Royal Navy has a separate diving unit,