Broadly speaking, the aircraft carrier and carrier tactics experimented with by the Royal Navy, specifically HMS Furious. Carried out the very first successful aircraft carrier launched air strike on 17/18 July 1918, the first landing of a aeroplane on a carrier deck (although strictly speaking Furious was still a seaplane carrier as the rear deck hadn't been fitted at that stage) and countless experiments with deck landing apparatus in 1918, 1919.
The Royal Naval Air Service's spiritual decendant, the Fleet Air Arm controlled by the Admiralty.