In 1915 Isaac returned to Britain. Due to the war he was unable to make a living. So although he opposed killing, he enlisted in the army to join the medical services.

However he was too short for regular regiments and so was sent to a 'Bantam' battalion (for men under five feet three inches tall) called the 12th Suffolk Regiment. It is said that Isaac was unsuited to Army life – being clumsy and absent minded, and he also encountered anti-semitism from both officers and soldiers alike. For example, in a letter written to his friend Schiff in October 1915 Isaac wrote:

"I don't mind the hard sleeping the stiff marches etc. but this is unbearable. Besides my being a Jew makes it bad amongst these wretches."

Isaac was eventually transferred to the 11th Battalion, The King's Own Royal Lancaster Regiment (KORL) and by June 1916 he was in the Somme trenches in France.

The colourful patriotic poster above is typical of the period, though it belonged to the 5th Battalion of the KORL rather than Isaac's own 11th Battalion. See a recruitment poster for Isaac's 11th battalion

Below is a detail of Isaac Rosenberg's entry in the official medal rolls for the KORL, it indicates that he received two campaign medals - the Victory medal and the British war medal. Medal rolls are available for viewing at The National Archives. See the research guide British Armed Services: Campaign Medals, and other Service Medals.

Apart from a spell of 6 months in the Royal Engineers working to move dead bodies away from the front line Isaac served with the KORL until his death. It was while in the trenches that he wrote many of his poems. On the next page you can read three of his poems.