January 1940 saw Marshall’s elder bother, James, conscripted. On 26 April, with little training, he was sent to France as the British Expeditionary Force fought to save France from German occupation. James was killed during the retreat to Dunkirk on 27 May 1940, aged 20.
On 22 January 1942, aged 18, Marshall was called up. Initially he joined the South Staffordshire Infantry Regiment based at Worcester. In May he was posted to the Suffolk Infantry Regiment where he continued his infantry training. On 27 November, he was transferred to the Westminster Dragoons, a tank regiment, where he trained first as a driver and then as a tank wireless operator and gunner.
In February 1944, Marshall was transferred to the 4th County of London Yeomanry (4CLY), another tank regiment – the “Sharpshooters”. Preparations for D-Day began, during which time Marshall played for the Regimental football team.
On 5 June 1944, the Regiment sailed for France.