Australian Army Major General. A decorated combat veteran of World Wars I and II, he rose in rank to become the commander of Australia's 7th Division. After attending Hurstville Superior Public School, he worked as an audit clerk with the New South Wales Government Railways and joined the cadets and then the 39th Battalion of the Australian Militia. In 1913 he was commissioned a lieutenant and joined the Australian Imperial Force (AIF) in June 1915. With Australia engaged in World War I, he departed for Egypt the following August with reinforcements for the 13th Battalion and participated in the Gallipoli Campaign. In March 1916 he was promoted to the rank of captain and assigned to the 45th Battalion. The following June he was sent to the Western Front in France and fought at the Battle of Pozieres two months later. He remained in the front line on the Somme into 1917 and led his men through the Battle of Messines in June of that year. His leadership amidst heavy losses earned Allen the Distinguished Service Order and a promotion to the rank of Major. In April 1918 he led his unit at the Battle of Dernancourt and then as an acting lieutenant colonel, in charge of the 48th Battalion, at Battle of Monument Wood. In June 1918 he went to England to attend the Senior Officers’ Course at Aldershot, in Hampshire. After Germany surrendered in November 1918, he was promoted to the permanent rank of lieutenant colonel and given command of the 13th Battalion. He was awarded the French Croix de Guerre for his service on the Western Front. In November 1919 his appointment with the AIF ended and he returned to Australia. He then became an accountant but remained active in the Militia. In 1933 he was promoted to the rank of colonel and placed in charge of the 14th Brigade. In 1938 he was promoted to the rank of brigadier general. In October 1939, right after the outbreak of World War II, he became commander of the 16th Brigade in the 2nd AIF's 6th Division. The following year, he was in North Africa, where his brigade fought the Italians at Bardia and Tobruk under Operation Compass, the first major Allied military operation of the Western Desert Campaign during World War II. In March 1941 he and his unit left North Africa for the ill-fated Greek campaign, following which he was awarded the Greek War Cross. He was then given command of the 7th Division, and commanded it in the invasion of Syria and Lebanon, against Vichy French forces. In August 1941 he was officially promoted to the rank of major general. In March 1942 he returned to Australia and the following August took charge of operations against the Japanese advance during the Kokoda Track campaign in Papua, New Guinea. While successful, he came under what many consider unfair criticism from US General Douglas MacArthur, the Allied commander in the South West Pacific Area, and the Allied land forces commander, the Australian General Thomas Blamey, for moving too slowly in pursuit of the Japanese across the Owen Stanley Ranges, and in October 1942 he was relieved of his command. Lesser appointments followed, but in October 1944, Blamey recommended that he be made a Knight Commander of the Order of the British Empire, but he was never appointed. He retired from the Australian Army in 1945, with 32 years of continuous military service. His other notable military awards and decorations include the Commander of the Order of the British Empire, the Companion of the Order of the Bath, the Volunteer Officers' Decoration, and was twice mentioned in World War I dispatches (whose name appears in an official report written by a superior officer and sent to the high command, in which is described the soldier's gallant or meritorious action in the face of the enemy). After the war he became a senior partner in a Sydney accountancy firm. He was an Associate of Commonwealth Institute of Accountants and a Fellow of the Institute of Chartered Accountants in Australia. He died at the age of 64.