On his return to active service, Roy achieved ten victories (two shared) in thirteen days. His first was a Hannover over Drocourt on 6 July. This was followed by three victories in the space of four hours on 8 July (two Hannover Cs and a Fokker D.VII); two on 13 July (a Hannover C and a Pfalz D.III); two on 15 July (two Fokker D.VIIs); and one on 18 July (a DFW C.V). Roy's final victory came the following day when he shot down a Hannover C over Cagnicourt. He is believed to be the first and only Indian flying ace of the First World War.