 Cobby shot down three German aircraft on 28 June and was recommended for a bar to his DFC, highlighting his then-current tally of 15 victories. On 15 July 1918, he and another pilot dived on five Pfalz scouts near Armentières, Cobby accounting for two of the enemy aircraft and his companion for one. The Australians were then pursued by four Fokker Triplanes but managed to evade their attackers. This action earned Cobby a recommendation for a second bar to his DFC, the citation noting that he had scored 21 kills to date and had "succeeded in destroying so many machines by hard work and by using his brains, as well as by courage and brilliant flying". The two bars to his DFC were gazetted on the same day, 21 September. On 16 August, Cobby led a bombing raid against the German airfield at Haubourdin, near Lille, the largest aerial assault by Allied forces up until then, resulting in 37 enemy aircraft being destroyed. The following day he led a similar attack on Lomme airfield and was recommended for the Distinguished Service Order as a result. Gazetted on 2 November, the citation for the award declared that "The success of these two raids was largely due to the determined and skilful leadership of this officer".
