In early 1885, in response to the fall of Khartoum and the death of General Charles Gordon during the British campaign against the Dervish revolt in Sudan, the colony of New South Wales raised a military contingent consisting of an infantry battalion, with artillery and supporting units, for service with the British. In an effort to enlist, Bridges travelled to Sydney from Narrabri, but by the time he had arrived, the force had already been raised. Nevertheless, due to concerns about Russian intentions in Afghanistan, the Australian colonies began expanding their military forces, and on 19 May that year he was commissioned as a lieutenant into the New South Wales Artillery. Initially his appointment was only temporary, but he was later offered a permanent position.