 Complete the following phrase:  At Jesau, the Gruppe began upgrading their aircraft to the Bf 109 F-4. On 14 April, II. Gruppe was ordered to Pilsen, where they finished the conversion. The unit then moved to Wien-Schwechat on 24 April before flying to Zürichtal, present-day Solote Pole, a village near the urban settlement Kirovske in the Crimea. There II. Gruppe participated in Operation Trappenjagd, a German counterattack during the 