Criminal Investigation Department (Ireland)

The Criminal Investigation Department (CID) in the Irish Free State was an armed, plain-clothed counter-insurgency police unit that operated during the Irish Civil War. It was organised separately from the unarmed Civic Guard police force. The unit was formed shortly after the truce with the British (11 July 1921) and disbanded in October 1923.

The CID was created by Michael Collins and many of its personnel were former Irish Republican Army fighters whom he had commanded during the Irish War of Independence. In particular, a number came from the Squad, a Dublin based IRA assassination unit. The unit had close links with the Army Intelligence and with a smaller 'Protective Corps' which was based in the same building, Oriel House on Westland Row, Dublin. Initially, they were put under the command of Liam Tobin. On 31 July 1922, it was taken out of the control of military intelligence and put under the brief of TD Joseph McGrath. Its commanding officer was Captain Pat Moynihan. Moynihan was given temporary transfer from his post as Head of Military Intelligence and with the rank of Captain took over Oriel House for this new force.

On 22 August 1922 (the same day as Collins' death in an ambush) the Criminal Investigation Department was officially formed to 'be distinct from existing police forces with separate headquarters under direct control of the Minister for Home Affairs.' It was formed from members of the National Army and the Irish Republican Police and was based at Oriel House. It consisted of over 100 heavily armed men and three women detectives who were 'cloaked' as typists and 'engaged in special duties connected with the detection of women engaged in hostilities against the Government.' The unit later reached a peak strength of 350 in February 1923.

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