Junkers Ju 87 with the Ju 87 A-0, the B-1s were returned discreetly to the Reich. The experience of the Spanish Civil War proved invaluable - air and ground crews perfected their skills, and equipment was evaluated under combat conditions. The Ju 87 had not been tested against numerous and well-coordinated fighter opposition; this lesson was learned later at great cost to the Stuka crews. All Stuka units were moved to Germany's eastern border in preparation for the invasion of Poland. On the morning of 15 August 1939, during a mass-formation dive-bombing demonstration for high-ranking commanders of the Luftwaffe at Neuhammer training grounds
Junkers J 1 a series of fully cantilevered all-metal monoplanes. Upon the outbreak of the First World War in 1914, Junkers decided to direct his efforts towards projects which would have potential military value. During this era, the majority of aircraft designers were relatively conservative and, save for some isolated examples, no advancements were achieved; according to aviation historian Charles Gibbs-Smith, the pioneering work of Hugo Junkers was a notable exception. It was Junkers' efforts, along with those of collaborators such as engineers Otto Reuter, Otto Mader, head of Junkers' "Forschungsanstalt", and Hans Steudel, director of Junkers' structural materials and testing department that