Junkers Ju 87 its pilot, Captain Mieczysław Medwecki, was killed. In air-to-air combat, Ju 87 formations were well protected by German fighter aircraft and losses were light against the tenacious, but short lived opposition. The Ju 87s reverted to ground attack missions for the campaign after the opening air attacks. Ju 87s were involved in the controversial but effective attacks at Wieluń. The lack of anti-aircraft artillery in the Polish Army magnified the impact of the Ju 87. At Piotrków Trybunalski I./StG 76 and I./StG 2 destroyed a Polish infantry division de-training there. Troop trains were also easy targets. StG 77 destroyed one
Junkers marked on the J-9's landing gear wheel covers. The corrugated duralumin wing and fuselage "skin" introduced in the J-series became a trademark of Junkers aircraft built in the 1920s and '30s. Development continued during the course of World War I, including a growing (but troublesome) partnership with Fokker, as the "Junkers-Fokker Aktiengesellschaft". Several Junkers designs were licensed to Fokker during this period. The visual similarity of Junkers and Fokker aircraft during the next decade, especially after Reinhold Platz adapted some of the Junkers design concepts, but mostly crafted in wood for the Fokker designs' wing structures instead of the all-metal