In Dublin, the War of Irish Independence (1919-1921) was an intense and dirty battle between military intelligence agents. While IRA flying columns fought the British Army and the Black and Tans in the countryside, the fighting in Ireland's capital city pitted the wits of IRA commander Michael Collins against the cloak-and-dagger innovations of British Intelligence chief Colonel Ormonde de l'Epee Winter. Drawing on detailed witness statements of Irish participants and documents and biographies from the British side, this history chronicles the covert war of assassinations, arrests, torture and murder that climaxed in the Bloody Sunday mass assassination of British intelligence officers by IRA squads in November 1920.