On September 20, 1920, the town of Balbriggan in County Dublin experienced a violent retaliation by the British auxiliary police force known as the Black and Tans. The attack was provoked by the assassination of a British official believed to be carried out by the Irish Republican Army (IRA). In response, the Black and Tans, infamous for their brutal tactics and aggressive enforcement methods during the Irish War of Independence, stormed the town, setting fire to homes, businesses, and other buildings. This not only resulted in significant property damage but also led to the deaths of two local men, Daniel O'Reilly and William H. Kelly, further intensifying local animosity towards British forces.

The events in Balbriggan illustrated the increasingly brutal nature of the conflict as the Irish War of Independence escalated. The Black and Tans, who had been deployed in 1920 to support the Royal Irish Constabulary, utilized violent reprisals as a strategy, which contributed to a cycle of violence affecting both soldiers and civilians. The widespread destruction in Balbriggan and the loss of life stirred significant unrest and led to increased recruitment for the IRA. Reports about the attack drew condemnation from various quarters, including journalists and politicians, which heightened awareness of the conflict in Ireland and British colonial policies.

The ramifications of the Balbriggan incident were profound, representing not only the struggle for independence but also an embodiment of the frustrations and anger of the Irish people against oppressive measures imposed by colonial rule. As a flashpoint, this attack exemplified the lengths to which the British would go in efforts to maintain control, while galvanizing support for Irish self-determination and the cause of independence. The event remains a notable chapter in the larger narrative of Ireland's revolutionary period.