The Battle of Cardiff (classified by US Army as Operation Welsh Fortress; in Ireland regarded as part of Operation Welsh Storm) was a military operation in which components of the US Army XI Corps and the US Marine Corps 2nd Division (a force totalling roughly 24,000 in number) defended the city of Cardiff and its environs from an attack by Irish Regulars, an attachment of English Workers Army infantry and armor, and the Welsh Workers Army, an associate group operation in and around the city itself.
Lasting November 2-December 6, 1952, the fighting destroyed large parts of Cardiff and involved heavy civilian casualties in an already war-torn city. The United States suffered roughly 5,000 casualties against 4,500 Irish and 1,200 EWA. The tactical victory was won after the 8th and 9th Battalions of the 2nd Division compromised the west and northwest lines of the enemy and were able to enter Cardiff to reinforce the Americans already there. Due to air and naval superiority, the Americans were always at an inevitable strategic advantage. Roughly 14,000 civilian casualties, roughly half of them fatal, are associated with this battle, and despite the victory many accusations of American atrocities emerged in the years after the Anarchy ended.