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 Ju 87 needed. Skilled workers had been called up for military service in the Wehrmacht. Junkers were able to supply 300 German workers to the Weserflug factory, and as an interim solution, Soviet prisoners of war and Soviet civilians deported to Germany. Working around the clock, the shortfall was made good. WFG received an official commendation. By May 1942, demand increased further. Chief of Procurement General Walter Herthel found that each unit needed 100 Ju 87s as standard strength and an average of 20 per month to cover attrition. Not until June–December 1942 did production capacity increase, and 80 Ju 87s were