Ernest Allen was born at Gin Gin, Queensland, on 8 October 1883. He was considered an expert horseman with considerable skill as a marksman and became champion of the Wide Bay region in Queensland in 1914. The 32-year-old farmer and grazier enlisted with the Australian Imperial Force on 5 July 1916. Two of Allen's brothers, Josiah and James, also enlisted that same day. Together the three brothers departed Sydney with reinforcements for the 49th Infantry Battalion aboard HMAT Ceramic on 7 October 1916.

Having been sent to England and then the Western Front, Allen and his two brothers fought at the battle of Messines on 7 June 1917. It was on this day that both of his brothers were killed in action. Allen frequently wrote letters home, describing the conditions on the front. His experiences there led him to write in one letter that he was quite pleased the 1916 referendum on conscription had failed, a sentiment shared by many other soldiers at the time.

In April 1918 the Australian 13th Brigade (of which the 49th Battalion was a part) was given the task of recapturing Villers-Bretonneux from the Germans. Ernest Allen was killed in action on 25 April 1918 while fighting to recapture the town. He is commemorated on the Villers-Bretonneux Memorial in France. Sadly, whilst Allen's family requested any and all information about his burial and belongings, the transport ship carrying his personal effects from England back to Australia was sunk by a German submarine. All they received were two photographs of his grave and his service medals.