On a sunny summer Wednesday 100 years ago, Dublin Brigade IRA carried out its biggest operation of the War of Independence.

A typical British portrayal of the attack as vandalism (The London Illustrated News)

Back in January Dáil Eireann President Eamon De Valera had insisted on a major blow against British rule in the capital city with high propaganda value. The Executive Council (Cabinet) agreed and Dublin Brigade was ordered to examine two possible targets – Beggar’s Bush Barracks, Depot for the Auxiliaries; or the Custom House, a key seat of British financial control which held local government and other financial records.

After reconnaissance the barracks was ruled out. So the Custom House was to be the target. The attack was intended as an ‘in-and-out’ bloodless coup, requiring about 30 minutes. There was no military guard on the building.

Planning was exhaustive and took several months. Plans of the building were obtained, senior officers did walk-throughs and logistics arranged. The chosen weapon was fire and the attack was scheduled for daylight, at lunchtime on a working day. Significant manpower was allocated for cutting off communications, sourcing and delivery of incendiary materiel, takeover and firing of the building and preventing a response from fire stations.

A key decision turned out to be the limited area of deployment of protective IRA forces, deliberately confined to the close environs of the Custom House on GHQ orders.

About 170 men were posted in the building to carry out the incendiary work, to round up staff and other occupants and seal off exits. The local 2nd Battalion provided the majority of these participants, with the Squad and ASU in support. Other units, including further ASU men, were tasked with providing outside screening forces.

On the day, the IRA successfully took over the building and detained the occupants. The 2nd Battalion men proceeded to scatter files, break up woodwork and soak offices with paraffin while the Squad and ASU guarded the staff and kept an eye out for crown forces.

But before the full job was complete, the alarm was raised with Dublin Castle and units of Auxiliaries with armoured cars and machine guns arrived on the scene. The lightly armed IRA and civilians were trapped in the burning building while a street gun battle broke out.

Auxiliaries at the Custom House (BN de F)

Nobody actually died in the fire but five IRA men attempting to break out were killed and four civilians (two Custom House staff and two innocent passers-by) also died. Around twenty others – IRA, civil servants and Auxiliaries – were wounded. Almost 100 IRA were captured.

Crown forces detain people for search and interrogation while Capt. Patrick O’Reilly lies dead on Beresford Place (NMI).
A group of IRA men under arrest guarded by Auxiliaries and military

The outcome of the attack caused controversy, not least about the loss of James Gandon’s architectural masterpiece. An inevitable result the Dáil regretted as a military necessity.

Arguments continue about the success or failure of the operation.

Burning of Dublin Custom House 1921
Assessing damaged records

Undoubtedly almost all the records were destroyed; and the required international press coverage of the Irish situation was achieved. Some argue it was a key factor leading to the Truce between the Irish and British in July 1921.

On the other hand, critics point to the high losses for the IRA or the ruined building. Some even bemoan the loss of the records.  

The attack has given rise to accounts of fear and panic, heroism and bravery, remarkable escapes, tragic deaths and unfortunate mishaps. To say nothing of the individual human stories by or about the participants – willing and involuntary – and by others who witnessed the amazing happenings near the River Liffey on 25 May 1921.

There are other fascinating sub-plots to the full story, such as the role of Dublin Fire Brigade in assisting the attackers, the possible source of the alarm and how small delays may have hampered total success.

This episode in the War of Independence in Dublin has become known as the Burning of the Custom House.