being disbanded altogether. In April 1923 shore-based strength amounted to a solitary squadron (Nb: possibly No. 230 Squadron RAF). A year later all that remained was one flight of torpedo bombers. Only five squadrons of ship-borne aircraft remained by April 1924. These reductions were not uniform across the service. The percentage reduction of the maritime component was far greater than non-maritime elements. The ten year rule (that there would be no major war for ten years) laid down in 1919 ensured the RAF was to be reduced by 50 percent, which downsized the maritime squadrons on the RAF to just five percent of its November 1918 strength. The Air Ministry justified this reduction of maritime aviation in light of the 'breakthrough' in ASDIC (sonar), and underwater detection technology capable of locating submarines. As 86 percent of the First World War maritime air effort had been expended on ASW it argued it was reasonable for a reduction in maritime expenditure in light of the technology now available. The lack of ASW development during the 1920s and 1930s was not entirely the fault of the Air Ministry. The struggle between the Admiralty and Air Ministry continued into the 1930s and the Admiralty lost sight of why it was pursuing its own air service for the Navy. It became a matter of getting revenge over the RAF for its success in defeating earlier attempts to break up the Air Force. It succeeded in forcing the return of the Fleet Air Arm (FAA) from the RAF in 1937, but made no effort to develop ASW formations. Instead it continued to believe in the supremacy of the capital ship and the FAA was meant to be suitable for fleet actions only. It was a mistake most of the major powers, in particular the Imperial Japanese Navy, made during the lead up to the Second World War. Throughout the inter war period, the Admiralty had been continually sceptical of the aircraft's ability to sink a surface vessel. It was regarded as merely a reconnaissance technology. This resulted in a lack of development of a maritime strike force and lost another early opportunity to garner support for Coastal Area/Coastal Command. In summation First Sea Lord David Beatty, 1st Earl Beatty proclaimed "[I] know of no operation in which the Navy and the Air [Service] have to co-operate in which the Navy would not play the more important