Timeline of The Irish Civil War - Hostilities

Hostilities

• 28 June – Michael Collins borrows two British 18-pounder field guns to bombard the Four Courts, marking the definitive start of the Civil War.
• Fighting breaks out in Drogheda between pro and Anti-Treaty units. One man on either side and a woman civilian are killed in a gun battle in the town. Many other civilians including the town's mayor are wounded. The Republicans are left in control of the town. The Anti-Treaty fighters blow up the railway bridge to the south of Drogheda, isolating it from Dublin.
• An Anti-Treaty fighter is killed in fighting Tipperary town.
• 29 June – British give Collins two more 18 pounders to increase the bombardment of the Four Courts. Free State troops storm the eastern buildings of the complex, losing 3 dead and 14 wounded.
• Oscar Traynor leads Anti-Treaty members of the IRA's 1st Dublin Brigade to occupy O'Connell Street in order to help the Four Courts garrison. His men also take up positions in York Street, South Circular Road, Capel Street, Parnell Square and Dolphin's Barn.
• Skirmish in Listowel County Kerry, Free State troops surrender their arms to Republicans.
• Free State troops surround republican fighters at Finner's camp, Donegal. After a two hour gun battle, two anti-Treatyites are killed and 50 surrender. Elsewhere in Donegal another 200 republicans are taken prisoner.
• 30 June – Anti-Treaty commander in the Four Courts, Paddy O'Brien is wounded by shrapnel. Ernie O'Malley assumes command. In the morning there is a truce to remove the wounded. Shortly afterward, a massive explosion destroys the western wing of the Four Courts and the Irish Public Records Office along with it. It is thought to have been caused when fires from the artillery bombardment set off munitions stored there, although Free State troops claim that the building was mined. 20 Free State soldiers are maimed in the blast. O'Malley surrenders the Four Courts when Oscar Traynor sends word that he cannot break through to help them. Members of the IRA Army Executive Liam Mellows, Rory O'Connor, Joe McKelvey and Dick Barret are among the prisoners, but O'Malley himself escapes.
• A Free State column under Commandant General Sweeney breaks up Anti-Treaty units in County Donegal. There are fire fights at Letterkenny, Buncrana and Bundoran. Casualties are reported, including at least one irregular killed and 200 taken prisoner.
• Anti-Treaty IRA fighters fire on National Army billets in Tralee, killing one soldier.