From 1941 through to 1942, JG 26 were fully occupied with defending German military targets in northern France and Belgium from RAF incursions. JG 26 defended airspace east of the Seine to the Dutch border, while JG 2 covered west of the demarcation line. JG 26 formally came under the command of Theo Osterkamp's "Jagdfliegerführer" 2. At the beginning of 1941 Galland had three experienced and successful "Gruppenkommandeur" under his command; Walter Adolph, Rolf Pingel and Schöpfel. Müncheberg and the recently arrived Josef Priller would be appointed to senior commands during the year after the loss of Pingel and Adolph in action and Galland to the high command. 1941 proved to be a successful period for JG 26 tactically. Galland and his "gruppen" could chose which RAF formations to engage, and when and how to engage them. In essence, the German and British units were fighting a reverse Battle of Britain. At the beginning of the year, JG 26 began converting to the Bf 109 F-2. The fighter was aerodynamically cleaner than the E variant, and could out perform the previous version considerably. The type was similar looking to the Spitfire V, entering service simultaneously and the two were comparable. The cannons were deleted from the wing; one cannon remained firing through the propeller hub, and two heavy machine guns remained fixed above the engine to fire through the propeller. I. and III. "Gruppe" began conversion at Dortmund and Bonn. Consequently, only III./JG 26 were equipped with the F by 28 June 1941—39 machines reported. By 27 September, I. "Gruppe" had the F-4 while II. "Gruppe" equipped with the Focke-Wulf Fw 190.