Wellwood originally served in an Australian militia unit, the
Royal Australian Garrison Artillery before he enlisted in the Siege Brigade of the
Australian Imperial Force on 1 June 1915. On his enlistment papers, he stated he was a born British subject working as a motor mechanic. He later transferred to the
Australian Flying Corps, and trained as a
Royal Aircraft Factory SE.5 pilot. By mid-1918, he had been assigned to No. 2 Squadron AFC. He scored his first aerial success on 1 August, destroying a German two-seated
Rumpler reconnaissance plane southeast of
Lille. On 12 August, he destroyed a
Fokker D.VII over
Licourt. Wellwood teamed with squadron mate
Adrian Cole to destroy a
DFW recon machine over
Epinoy on 25 August. In September 1918, Wellwood struck twice, driving a Fokker D.VII down out of control on the 6th, and setting a
Pfalz D.III afire on the 24th. Wellwood's final two victories were achieved on 4 November 1918; in separate patrols, he destroyed a Fokker D.VII and drove down another out of control. which was personally presented by General
Sir William Birdwood on 20 March 1919. ==Postwar==