He served with the Australian Army during World War I and spent most of his service tunnelling under the front line trenches in France.

Hillman worked on water supply projects including being executive engineer on the Lower Bickley Brook Reservoir.

[3] In 1915, when applying for a commission, Hillman was employed as an assistant engineer in the Perth District Water Supply Department.

They were employed by the British in the Wytschaete, Fromelles, Laventie, Fauquissart, Lens, Loos, Arras, Givenchy, Vermelles and Le Tilleloy sectors.

Two weeks later, on 21 February 1919, he marched out to England for demobilization, returning to Australia on Sardinia, which departed from London on 19 April 1919.

On 3 June 1918, the award of the Military Cross to Captain Arthur James Hillman for gallant and distinguished service in the field was published in the London Gazette.

He was survived by his wife and six young children including Robert Hillman, who later became the Director of Engineering at the Public Works Department.