Thomas William Dickinson joined the Australian Imperial Force with his younger brother Richard Stanley Dickinson. The brothers were allocated consecutive regimental numbers. The brothers embarked from Melbourne with the 7th Reinforcements for 39 Battalion on 19 February 1917.

Following training in England Private Dickinson proceeded overseas to France in April 1918 where he joined the 38th Battalion in the field. He served with the 38th Battalion until the war ended and he returned to Australia in July 1919.