The Belfast Brigade of the Irish Republican Army (IRA) was formed in March 1921 during the Irish War of Independence, when the IRA was re-organised by its leadership in Dublin into Divisions and Joe McKelvey was appointed commander of the Third Northern Division, responsible for Belfast and the surrounding area. There were three battalions within the Brigade, the 1st in West Belfast, the 2nd in North Belfast and the Third in East Belfast. Most of the Brigades attacks on Crown forces were carried out by an Active Service Unit within the 1st battalion, led by Roger McCorley.