 Complete the following phrase:  Grinnell-Milne eventually returned to aerial combat with No. 56 Squadron RAF, flying the S.E.5a. On 5 October he destroyed a balloon south-west of Busigny. On 21 October he was appointed a flight commander with the rank of acting-captain, and celebrated by destroying a Fokker D.VII north of Bousies the same day. He destroyed and drove down two more D.VIIs over the Mormal Woods on 29 October, and destroyed his fifth and final aircraft, another D.VII, on 3 November north-east of Valenciennes. A week later 