Casualties throughout the War meant that many of the original battalions were to be amalgamated or disbanded as hostilities continued. In early 1918, on re-organisation, 107 Brigade consisted of the 1st and 2nd (Regular) and the 15th (Service) Battalions of the Royal Irish Rifles. In March 1918 the 36th Division, in the St Quentin Sector, was part of the Fifth Army and it was upon this Army that the main weight of the German Spring Offensive fell. The retreat which followed ended on 29 March and the Ulster Division moved north to the Ypres Salient. It thereafter took part in the successful offensive operations, which culminated in the cessation of hostilities in November 1918.