Ambrose Edmund Rosser was born in Ballarat, Victoria, was single and a Printer when he enlisted in the 39th Battalion, D Company on 29 March 1916 at the age of 18. His unit embarked from Melbourne, Victoria, on board HMAT A11 Ascanius on 27 May 1916. He was hospitalised briefly suffering from scabies in January 1917. Such an illness was not uncommon throughout those in the trenches. He transferred to the 1st Machine Gun Battalion in April 1918 and was sent to attend Army Infantry School in May. By the time he re-joined his unit from school the hostilities were coming to an end. He returned home aboard the Hospital Transport Persic on 29 August 1919.

His older brother, Pte Mark James Rosser, 8th Bn, (Tree No. 1653)
Tree No. 2054