Thomas was born and educated in London, England. He came to Australia about 1912 and worked as a Farm hand at the property Clinton, west of Inverell. He enlisted in September 1915 as a Private with the 30th Battalion, 3rd Reinforcements.
After several months in camp at Liverpool, he sailed from Sydney for Egypt on the HMAT A70, Ballarat. At Suez he joined the 10th Field Artillery, was sent to France in June 1916 and promoted to Bombardier. On 28th November 1916, Thomas was recommended for a Military Medal for his efforts under heavy enemy fire on two occastions during the month.
Bombardier Thomas Dawson was killed in action on 7 December 1916 at Albert, France. He was just twenty three years old. Thomas was buried at Bernafay Wood British Cemetery, Montauban, France.