The 3/4th Battalion was formed at Northampton on 12 May 1915. It moved to Windsor Great Park in August, and then to Halton Park in October. On 8 April 1916 it was renamed the 4th Reserve Bn, forming part of the East Anglian Reserve Brigade at Halton. In August 1917 the battalion moved again, to Crowborough, where it later absorbed the 2/4th Bn. In September 1918 it moved to St Leonards-on-Sea and remained there until disbanded on 28 July 1919 after the end of the war.