Hugh Campbell Thomson was born in Clunes, Victoria, was single and a Student in Ballarat when he enlisted with the 5th General (Victorian) Reinforcements on 10 November 1917 at the age of 18. His unit embarked from Sydney, New South Wales, on board RMS Orontes on 5 June 1918. He was appointed as an Acting Corporal on 3 December 1917 and promoted to Lance Corporal on 11 February 1918. The remainder of his military service seems to have gone without major incident, illness or injury and he returned home to Australia on 13 July 1919.

His brother, 2nd Corporal Frederic McLeod Thomson of the 57th Bn also served, returning to Australia, 22 July 1919
Tree No. 3539