The Battle of Willow Creek, also occasionally referred to as the Battle of the Willows, was an engagement from September 2-5, 1952 that was the first major American engagement in the Welsh Campaign of the English Adventure in an uninhabited region of central Wales. The American XI Corps encountered the Irish Regulars 5th Division at a place the locals referred to as the Willows due to a propensity of willow trees in a low valley, and the Irish were soon thereafter reinforced by a small force of EWA forces.
The battle was the most violent for the Americans in 1952 and, until the Battle of Birmingham, was the most violent in the war. After three days of heavy, bloody fighting where the two sides literally fought for every foot of ground, the Americans defeated the Irish and pushed out of the valley, having suffered over 1,000 dead and 2,500 wounded. The losses amount for the highest in a three-day period for the US Army until the Siege of Gateshead in early 1956. The battle was significant for setting up the broad Irish counterattack known as the "Welsh Storm" which culminated with defeat for the Irish and the EWA at Cardiff in November.