Dee ihe na-esote paragraf a - Allen bụ onye e nyere ọrụ n'afọ 1913 ma sonye n'òtù ndị agha Australia (AIF) na 24 June 1915. Allen banyere ụgbọ mmiri gaa Ijipt na ndị enyemaka maka 13th Battalion n'August. N'ọnwa Machị afọ 1916, e mere ya onyeisi ndị agha ma kenye ya n'òtù ndị agha nke 45. Ọ bịarutere France na 8 June 1916 ma lụọ ọgụ na Agha nke Pozières n'August. Allen nọgidere n'ihu agha na Somme n'afọ 1917 ma duru ndị ya n'agha Messines na June. Onyeisi ya n'agbata nnukwu mfu mere ka Allen nweta ihe nrite nke Distinguished Service Order ma bulie ya n'ọkwa onye isi na July. Ọ gara n'ihu na-edu ndị mmadụ n'agha, n'agha nke Dernancourt n'ọnwa Eprel afọ 1918, mgbe ahụ dịka onye na-arụ ọrụ dịka Lieutenant Colonel, na-elekọta ndị 48th Battalion, n'agha nke Monument Wood
Ọ dị mma.