Who invented the airplane in World War one?
The aeroplane exists before WW1: War accelerates technology. The methods of aerial combat moved from the pistol & shotgun to the machine gun, with deflecting plates & then interruptor gearing, and the addition of bombs dropped over the side & then mounted in racks. Notable aircraft in WW1 include the Fokker Eindekker, the Albatross, the Roland C II Walfisch & the Fokker D VIII on the German side. The British used the Sopwith Camel, the SE 5 , the Bristol F2b Fighter and others. The French Spad VII & XIII were famous aircraft as well. The to your question is that the British, French & Germans all developed the Aeroplane in WW1 to a very different standard in a very short period of time.