An Garda Síochána ("The Guardian of the Peace") is the national police and security service of Ireland. It was formed by the Irish Government following the July 1921 truce of the Irish Civil War to replace the Royal Irish Constabulary. The Dublin Metropolitan Police were merged into the Garda in 1925.

An Garda Síochána is the main law enforcement agency in the state, acting at local and national levels. Its roles include crime detection and prevention, drug enforcement, road traffic enforcement and accident investigation, diplomatic and witness protection responsibilities, and community policing services. The Garda is principally an unarmed force; detectives and units such as the regional Armed Support Units (ASU) and the national Emergency Response Unit (ERU) are commissioned to carry firearms.

An Garda Síochána is headed by the Garda Commissioner, who is appointed by the Irish Government. It is organized into four geographical regions: Eastern, North Western, Southern, and Dublin Metropolitan Region, in turn broken into divisions, districts and sub-districts. Additional units exist for specific areas of work such as Crime and Security Intelligence, Organized and Serious Crime, and Community Engagement and Roads Policing.

Sources:

"Garda Síochána." Wikipedia. December 20, 2023. https://en.wikipedia.org/wiki/Garda_S%C3%ADoch%C3%A1na

"Organizational Structure." An Garda Síochána website. December 20, 2023. https://www.garda.ie/en/about-us/our-history/

"Our History." An Garda Síochána website. December 20, 2023. https://www.garda.ie/en/about-us/our-history/