On 8 June 1941, the bulk of JG 53's air elements moved via Jever, in northern Germany, to Mannheim-Sandhofen. There the aircraft were given a maintenance overhaul prior to moving east. On 12 June, III. "Gruppe" was ordered to transfer to a forward airfield at Sobolewo. On 21 June, the "Geschwaderkommodore" (wing commander) of JG 53 and its "Gruppenkommandeure" were summoned to nearby Suwałki, where "Generalfeldmarschall" (field marshal) Albert Kesselring gave the final instructions for the upcoming attack. Wilcke briefed his pilots that evening.