The Germans during WWII developed the first working and flying jet engines, which was a huge technological leap at the time.
IIRC, the Germans copied the jet engine theory and basic design/idea from a technical trade publication published in the 1920's that had been created by a guy in England.
If you ever have a chance to visit the Wright-Patterson Air Force Museum in Dayton, OH, you should take the opportunity with zeal. While I love the WWII exhibit, the WWI hall is absolutely stunning. As you walk the giant room, they show you the development of both planes and engines during the Great War.