The 3rd Cork Brigade, also known as Third (West) Cork Brigade was a unit of the Irish Republican Army that operated in the western areas of County Cork during the Irish War of Independence. The Brigade was commanded by Tom Barry for most of the conflict and was responsible for the Kilmichael Ambush, which resulted in the deaths of 18 members of the Auxiliary Division, and the Crossbarry Ambush, during which the Brigade escaped encirclement by 1,200 British troops. It was one of the most active brigades during the conflict.