The year 1917 followed the costly battles of the Somme, which ended in on 14th November 1916. 21st division had played a part in many of the actions of these battles and had finally expunged its poor reputation wrongly gained at Loos in September 1915. However it had yet to become one of the finest of the BEF but 1917 would help to solidify that reputation.
The battles of 1917 would see a move further north initially with the battle of Arras, conducted by General Allenby's third army and then back to the BEF's old battle ground of Ypres. The Battles of 3rd Ypres, more commonly but wrongly known as the battle of Passchendeale would capture the modern imagination, with the rain and mud ending those battles and ingraining the partially true myth that the western front was all mud and rain. The division would play significant parts in both of these battles and the subsiduary actions surrounding these and would end the year fighting in the brilliantly started but poorly finished battle of Cambrai.