Volume I of the Grenadier Guards in the Great War of 1914-1918 takes the record of the four batallions to the end of 1915.The Grenadier Guards began the war with three batallions. When war was declared the 4th ( Reserve )Battalion was formed. On 14th July 1915 another Grenadier batallion was formed and numbered the 4th, the Reserve batallion then became the 5th.