On the outbreak of war, the battalion was embodied at Hertford under the command of Lieutenant Colonel Brand. It joined the British Expeditionary Force in France on 6 November 1914, serving in the trenches during the closing stages of the First Ypres. Later that month the battalion joined the 4th (Guards) Brigade of the 2nd Division. Due to this attachment, it acquired the nickname the "Hertfordshire Guards", and adopted many Guards’ peculiarities, including the numbering of its companies. In January 1915 Lieutenant Colonel Croft took command and the following month the battalion supported the 1st Irish Guards and 3rd Coldstream Guards in their seizure of the Brickstacks position at Cuinchy. In May it was again in action during the Battle of Festubert, consolidating the advance of the Irish Guards under heavy shellfire. On 19 August 1915 it was moved to the 6th Brigade within the same division, in time for the Battle of Loos. On 27 September the battalion, alongside 1st King's (Liverpool Regiment), was due to assault the enemy lines beside Cuinchy. The attack however, was cancelled due to the failure of the gas released as its preliminary to impact the enemy.