“It was a dull morning. A slight mist overhung the river and when the first observers reached O’Connell Bridge the familiar green dome of the attacked building was obscured. But from the south side of the river the sudden flash of the gun could be seen and down the wide alley of the Liffey come the crash of shell and bomb and the sustained rattle of the smaller arms.”

Weekly Freeman’s Journal 01 July 1922

On June 28th 1922, the Irish Civil War began. The National Army attacked the anti-Treaty troops who had occupied the Four Courts under Rory O’Connor since April. An intense battle between the two sides ensued. From the outset the National Army, had better weapons, albeit supplied by the British Army had the advantage over the anti-Treaty side. But the IRA held their own, for two days, until a massive explosion, ripped through the building, razing it to the ground, left them no choice but to surrender. In spite of the destruction there were relatively few causalities.

The cause of the explosion is contested in the historiography, though the GHQ Irish Army issued a poster the following day: “Public Records Office destroyed with all its historic documents through fire caused by Irregulars’ explosion of mine.”

https://www.lawsociety.ie/gazette/in-depth/the-walls-came-tumbling-down

The bombardment of the Four Courts signaled to the IRA divisions throughout the country to mobilise and prepare to take on the Free State Army.

“This action caused IRA units around the country to take sides and most, especially in the south, sided with the anti-Treaty faction, now headed by Liam Lynch. Eamon de Valera initially rejoined the IRA as an ordinary volunteer…”https://www.theirishstory.com/2012/07/02/the-irish-civil-war-a-brief-overview/#.YqtVaB17nVo

Sources

Weekly Freeman’s Journal 01 July 1922

https://www.historyireland.com/the-battle-of-the-four-courts-28-30-june-1922/ By Michael Fewer

https://www.lawsociety.ie/gazette/in-depth/the-walls-came-tumbling-down