The present book describes the development history of turbojet engines, mainly in the web-type triangle Great Britain (USA) - Germany - Switzerland from early beginnings in the 1920s up to the first practical usage in the 1950s, before the still unbroken, grand impact of aero propulsion technology on global air traffic started. interconnections are highlighted, including the considerable impact of axial-flow compressor design know-how of the Swiss/German company BBC Brown Boveri & Cie. on both sides. The author reveals significant undercurrents which led to a considerable exchange, and thus change in understanding of the technical-historical perspective, especially in the decisive years before WWII, and thus closes gaps in the unilateral views of this ground-breaking technical advancement. The old 'Whittle vs. von Ohain Saga' is not repeated in full, but addressed in sufficient detail to understand the considerably enlarged narrative scope.