Of the Welch Regiment's thirty-four battalions active during the war nineteen served overseas in France, Belgium, Gallipoli, Egypt, Syria and Mesopotamia and Macedonia. Three members of the regiment were awarded the Victoria Cross for valour during the conflict. 7,679 Officers and other ranks gave their lives for their country.

Later the regiment was awarded seventy battle honours, of which ten were selected for display on the King's Colour of the regular and TA battalions. In 1919, the TA and Service Battalions stood down and the cadres of the 1st and 2nd Battalions, on being brought up to their established strength at Pembroke Dock, prepared for peacetime service.