Marshall John Egan seems to have been eager to go to war and proved to be a good soldier. He trained for 12 months before enlisting with the CMF at Albert Park, Victoria, then enlisted when he was eighteen and seven months old. A tinsmith by trade, he was 5' 7" tall, with a fair complexion, grey eyes and auburn hair. He began as a private, then embarked with his Company on the Orsova on 1 August, 1916, disembarking at Plymouth, England on 14 September. On 5 December, 1916, they were sent on the Princess Victoria from Folkestone to France, to fight with the 57th Battalion. Marshall Egan was taken on strength on 24 December, 1916 and was to prove to be an able soldier, made Lance Corporal on 4 February 1917 and promoted to Corporal on 3 August, 1917. 

The 57th Battalion had already been through several major battles on the Western Front, at Fromelles in July, 1916. Marshal Egan would have fought at Bullecourt and Ypres in early 1917 and at Polygon Wood in September 1917. Certainly, he had two stays in hospital, in March and April, with trench foot as a result of being at the front. In 7 October, 1917, he was sent back to the AIF Depot in the UK for duty with B Company, 15th Training Battalion and from 1-30 November, attended a course at Tidworth UK and 'qualified as 2nd Class with fair working knowledge of the Lewis Gun'.

He rejoined the 57th Battalion on 30 January 1918. The collapse of the Russian Empire in November 1917 meant an increased German offensive on the Western Front in early 1918. The Battle of Villers-Bretonneux, where so many Australian soldiers lost their lives was to happen in late March, but by then Marshall Egan was dead. He had been killed just a month after his return on 11 March, 1918, and was buried at La Plus Douve Farm Cemetery, Belgium, near Messines. His grave is No.10, Row B, Plot 13. He is remembered on the roll of Honour card 145, and Panel 163 at the Australian War Memorial.

When Marshall Egan enlisted he gave his next of kin as his widowed mother, Mrs. Bella Egan, at 395 Victoria Parade, East Melbourne. She subsequenty shifted to 396 Albert St., then to 130 Gipps St, and finally to 62 Commonwealth St., Sydney. Unfortunately, her son's medals and a letter from a friend of his in London, failed to reach her, as did his war gratuity. The letter reveals that there were other younger boys in the family. Perhaps they shifted from boarding house to boarding house. At one stage, she  briefly changed her name to Healy.