On the 1st July 1916 began the great series of battles on the Somme, the Regiment's part in which will be described, and almost immediately calls were made for drafts of all ranks to fill the very serious gaps caused by the heavy casualties sustained by the 1/4th Battalion during the battle of Gommecourt; and between this date and the middle of October when the 56th Division was finally withdrawn from the Somme battles a total of some 30 officers and 400 other ranks were despatched. These very heavy calls naturally depleted the ranks of the home Battalion very seriously and took nearly all the "Derby" recruits who had joined in the previous March. With the object, apparently, of effecting an ultimate economy in staff, a reorganisation of considerable importance took place on the 1st September 1916 among the whole of the 3rd line units of the Division. So far as the Fusilier Brigade was concerned this took the form of amalgamation of the four existing battalions into two, the 1st and 2nd Battalions becoming the 1st (Reserve) Battalion, and the 3rd and 4th Battalions becoming the 3rd (Reserve) Battalion. Each of these new battalions for the time being retained a double establishment of officers, warrant officers and N.C.O.'s and were organised in eight companies till the despatch of personnel on draft permitted a reduction to be made. The composite battalion was made responsible for the provision of reinforcements and for the reception of ranks returned from overseas for each of the two Regiments of which it was composed. These amalgamations of necessity involved extensive repostings of officers, in particular among those of senior rank. Command of the new 3rd (Reserve) Battalion was assumed by Lieut.-Col. T. Montgomerie Webb, formerly commanding the old 3rd (Reserve) Battalion, Major G. H. M. Vine being appointed second in command. The duties of Adjutant, Quartermaster and Training Officer respectively were also assumed by officers of the old 3rd (Reserve) Battalion (namely, Capt. McGlashan, Capt. Coombe and Major H. Moore, M.C.), the officers who had previously held the corresponding appointments in the old 4th (Reserve) Battalion being posted as follows:-- Capt, F. A. Coffin (Adjt.) to Brigade Staff. Lieut. Fullalove (Q.M.) to new 6th (Reserve) Battalion. Capt. F. C. Grimwade (Training Officer) to command A Company new 3rd (Reserve) Battalion. Col. Vickers Dunfee was appointed to command the new 1st (Reserve) Battalion, an appointment which he retained until his demobilisation in December 1918.