At the outbreak of WWI, at least four aircraft (including a German designed bi-plane) were based at Killingholme, tasked with defending the nearby oil depot.
In mid 1914, the first hangar was erected, a wood and canvas Bessonneau type. This was follow by the first of four 68 x 77 ft seaplane sheds which were completed in September 1914. In October the Bessonneau structure was dismantled and a seaplane slipway measuring 700 x 60 ft was constructed, allowing access to the River Humber. Landplanes continued to use the grass strip. A further hangar measuring 177 x 56 ft was added as the number of aircraft increased.
By the end of 1914, Killingholme’s complement of aircraft grew as several Sopwith Scouts arrived and were soon employed on anti-submarine duties. Seaplanes also started to make an appearance in response to the increasing U-boat menace.
The large size of the newer seaplanes coming into service dictated the need for an even larger hangar and during 1916 the largest one ever constructed in the county was completed, measuring an enormous 800 x 900 ft. Later that year, two further hangars measuring 200 x 100 ft were constructed as well as a further two slipways measuriung 850 ft long by 35 ft wide.
During the summer of 1917 it was decided that Killingholme would be transferred to the United States Navy, who would assist with North Sea Patrol work. The first American forces arrived in early 1918 and had worked up an operational strength by May of that year, undertaking coastal patrols in Short – manufactured seaplanes. The main body of US personnel arrived 1 June 1918 on the USS Jason, which also carried Curtis flying boats. The Americans stayed at Killingholme until January 1919, when the station was handed back to the RAF, albeit briefly,as the station closed in 1920.
A field trip to the site in 2012 revealed only the physical remains of RNAS Killingholm to be a decaying seaplane slipway and a few support piles of a second slip, normally hidden at high tide.