
Les Thiess undertakes his first independent road work contract for Queensland’s Department of Main Roads on the Darling Downs.

The firm of Thiess Bros is formally registered in Toowoomba by Pat and Bert Thiess, and the firm of Horn & Thiess is formally registered in Toowoomba by Henry “Stumpy” Horn and Les Thiess. They successfully tender for the Kilkivan roadworks job, removing 50,000 cubic yards of earth.

Thiess Bros completes the 104-foot-deep Heifer Creek Road Cutting between Gatton and Warwick - the deepest in Australia at the time. Demonstrating their ingenuity, they decide it is more efficient to carve a cutting, rather than following the specifications for a tunnel. A Brisbane newspaper dubs them “the men who eat rocks and stones”.
Thiess Bros wins its first job in NSW - sinking the Young Australia tank for New Occidental Gold Mine. This project marks Thiess’ first foray away from roadworks and building site preparation.
Thiess Bros is hired by the Allied Works Council and US Army to complete a series of major construction projects including roads, military camps and emergency airstrips around Australia.

Australia is hit by a coal shortage which presents an opportunity for Thiess Bros to diversify its operations. They successfully tender for two contracts to remove the overburden at Blair Athol Coal Mine in Queensland and Muswellbrook Coal Mine in New South Wales. These contracts mark the beginning of Thiess’ long association with mining.

Thiess Bros Pty Ltd is incorporated.

Thiess Bros wins a ploughing scheme contract as part of a combined effort between the British and Queensland Governments to help fill Great Britain’s post-war grain and meat needs.
Thiess Bros undertakes the earthworks for the duplication of Longwarry – Yarragon Line. This is the company’s first rail project and sets the foundations for its future in rail.

Thiess Bros salvages scrap metal from the Territory of Papua New Guinea, shipping US Army trucks, cranes and machinery to Australia. This equipment gives them an advantage over the competition and becomes a major factor in securing its future involvement in coal mining.
Thiess Bros builds the Bostock Dam in Victoria and Gara River Dam in New South Wales. These mark the beginning of the company’s substantial involvement in dam constructions throughout Australasia and the near Pacific.
Thiess undertakes the reclamation of swamp land at Currumbin Creek and Palm Beach, building the first canal development in the area. They later go on to build a large portion of the waterways in the Gold Coast area.

Thiess Bros’ Mt Isa area operations are established with the building of the Corella Dam for Mount Isa Mines. Over the next two years, they construct dams, water mains and roads in the region.