 Lloyd George wrote an angry letter to Collins which included the line "...still less can Mr. Rory O'Connor be permitted to remain his followers and his arsenal in open rebellion in the heart of Dublin... organizing and sending out from this centre enterprises of murder not only in the area of your Government..."

On 28 June 1922, after the Four Courts garrison had kidnapped Ginger O'Connell, a general in the new Free State Army, Collins began shelling the Four Courts with borrowed British artillery.British soldiers still in Ireland and expert in the use of their cannons helped bomb the Four Courts.O'Connor and 130 men surrendered on 30th June and was arrested and imprisoned in Mountjoy.