Junkers Ju 87 had been ineffective and disorganised, and as a result, "Stuka" losses were mainly due to ground fire. 120 machines, one-third of the Stuka force, were destroyed or damaged by all causes from 10 May to 25 June 1940. For the Battle of Britain, the Luftwaffe's Order of battle included bomber wings equipped with the Ju 87. Lehrgeschwader 2's IV.(St), Sturzkampfgeschwader 1's III. Gruppe and Sturzkampfgeschwader 2's III. Gruppe, Sturzkampfgeschwader 51 and Sturzkampfgeschwader 3's I. Gruppe were committed to the battle. As an anti-shipping weapon, the Ju 87 proved a potent weapon in the early stages of the battle. On 4
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