Marshall recalled the horrors of the battlefield and his memories of seeing many of his comrades blown to bits by enemy shells or mown down in No Man's Land by a hail of bullets.
He was present on the Somme for the first day of the offensive in which over 20,000 troops were killed in the first several hours, with 40,000 more injured, making the battle one of the heaviest death and wounded tolls of the war.
As a result of his unit being kept back during the Somme, Marshall was not credited with being the last veteran of the opening day; nonetheless, he remembered the trauma and horror of that campaign and the images on the battlefield remained with him.
On his return he joined the Machine Gun Corps and fought at the Battle of Cambrai where he was captured as a Prisoner of War by the Germans.
In the final decade of his life, Marshall was awarded the Legion d’honneur and appeared on numerous television shows as well as attending a veterans' party at Buckingham Palace.