However others escalated their activities against republicans and in March 1920 Collins asked Dick McKee to select a small group to form an assassination unit.
[4][5][6] Sometimes, as occasion demanded, the Squad was strengthened by members of the IRA Intelligence Staff, the Active Service Unit, munition workers and members of the Dublin Brigade, Tipperary Flying Column men, Dan Breen, Séumas Robinson, Seán Treacy and Seán Hogan, and also Mick Brennan and Michael Prendergast of County Clare.
The munitions workers included Mat Furlong, Sean Sullivan, Gay McGrath, Martin O'Kelly, Tom Younge and Chris Reilly.
Two of the executions by the Squad were the killing on 21 January 1920 of RIC Inspector William Redmond of the G Division[7] and on 2 March 1920 of a British double agent John Charles Byrnes.
Given carte blanche in its operations by Wilson, the Cairo Gang adopted the strategy of assassinating members of Sinn Féin unconnected with the military struggle, assuming that this would cause the IRA to respond and bring its leaders into the open.
The best-known operation executed by the Apostles occurred on what became known as Bloody Sunday, 21 November 1920, when British MI5 officers, linked to the Cairo Gang and significantly involved in spying, were shot at various locations in Dublin (14 were killed, six were wounded).
The elimination of the Cairo Gang was seen in Dublin as an intelligence victory, but Lloyd George commented dismissively that his men "... got what they deserved, beaten by counter-jumpers...".
Under the influence of Daly and Michael Collins, most of the Guard took the Free State side and joined the National Army in the Irish Civil War of 1922–23.
In October 1923, Commandant James Conroy was implicated in the murder of two Jewish men, Bernard Goldberg and Emmanuel 'Ernest' Kah[a]n. He avoided arrest by fleeing to Mexico, returning later to join the Blueshirts.