Throughout its existence the brigade was assigned to the 53rd (Welsh) Infantry Division and was composed almost entirely of Territorial battalions from the Royal Welch Fusiliers.

The North Wales Brigade (as it was originally known) was created in 1908 under the Haldane Reforms when the Volunteer Force and the Yeomanry were merged to create the Territorial Force and was composed of the 4th (Denbighshire), 5th (Flintshire), 6th (Carnarvonfonshire and Anglesey) and 7th (Merioneth and Montgomery) Volunteer battalions of the Royal Welsh Fusiliers.

[8] The Territorial Army, and 53rd Division, was mobilised in late August/early September 1939, due to the situation in Europe becoming increasingly worse.

[9] 53rd (Welsh) Division spent the next few years training for the planned Allied invasion of Normandy (Operation Overlord).

In March divisional HQ and the brigade and ancillary HQs took part in 'Exercise Shudder' to study 'thrust line' technique, then in April the whole division was engaged in 'Exercise Henry' on the South Downs training area; this included a river crossing and full-scale simulated attack.

[10] The brigade landed in Normandy on 23 June 1944 and fought in the campaign in North West Europe until May 1945, including the fighting on the Odon (Operation Epsom), around Caen, Mont Pinçon (Operation Bluecoat) and Falaise, in Normandy, at 's-Hertogenbosch in the Netherlands, and the fighting in the Reichswald (Reichswald) before finally invading Germany itself.

During this action, Captain Tasker Watkins, commanding B Company of the 1/5th Battalion, Welch Regiment, personally led a charge across a heavily defended stretch of open ground, reaching and personally eliminating an enemy position in spite of his companies' very heavy losses.