Charles Cooper was aged 37 when he enlisted on 7 July, 1915. He was placed in the 8th Field Artillery Brigade at Broadmeadows and subsequently was moved to Maribynong to join the Australian Veterinary Section. He named as his next of kin his wife, Mrs. N.L. Cooper, whose address was 16 Brunswick St. South, East Melbourne (now Morrison Place) though he gave his own address as Eskdale Rd., Caulfield.  It was unusual to have her own initials, not his, but perhaps they were separated. His occupation was named as horse trainer .  

Charles Cooper embarked from Melbourne on HMAT Medic on 20 May, 1916. There were five members of the AAVC on board, including him, all Sergeants with the 8th FAB: Donald Granter 19583; Cyril Dixon Brown 19584; Morris Clarence Sallman 19585; Charles Cooper 19586; Harold Lindsay Cameron 19587.Only two have service records online from the National Archives in Canberra, Donald Granter and Morris Sallman. There are no records available for the other three. From the two available records, it would seem that the Medic docked at Plymouth and the men were sent on to France. No other information about Charles Cooper is available. His name does not appear on the nominal roll and with no service record for him, Brown or Cameron, it is not clear what happened to them. Charles Cooper's name is too common to pick up on Birth, Death or Marriage Indexes, or on the Electoral Rolls.