Based in the Sinai Desert and Palestine, Murphy was initially responsible for No. 1 Squadron aircraft maintenance; his achievements saw him mentioned in despatches in 1917. He then trained as a pilot with the RFC in Egypt, where he obtained a temporary commission as a second lieutenant on 24 October. He flew with the RFC before returning to No. 1 Squadron in Palestine. During 1918, Murphy saw combat over Jordan, operating Bristol Fighters. On 12 August, he and his observer were selected to join Colonel T. E. Lawrence and his irregular Arab army in the Hejaz near Daraa, providing air cover and reconnaissance. Credited with bringing down two enemy aircraft while supporting Lawrence's troops, Murphy was awarded the Distinguished Flying Cross for his "keenness, reliability and boldness".