The 2nd Battalion under Commandant Thomas MacDonagh occupied Jacob’s biscuit factory on Bishop Street, almost a mile to the south of the GPO. Major John MacBride was second in command with Michael O’Hanrahan next in line. The garrison also included Gerald Boland, Michael Hayes and Peadar Kearney, who wrote the words of the national anthem, ‘The Soldiers Song’.

The building was a massive triangular structure filling most of the area between Peter Street and Bishop Street. It was difficult to assault because it was surrounded by a labyrinth of streets and small houses which would hinder the use of artillery. It had two tall towers which provided a view over much of the city. MacDonagh had approximately 130-150 men, supplemented by some Fianna Éireann and Cumann na mBan. He posted men in buildings in Camden Street, Wexford Street, Aungier Street and other streets in the area, making Jacob’s all the more difficult a target for the military.

Within hours of the garrison taking over, a company of military travelling from Portobello Barracks to strengthen the garrison at Dublin Castle was put to flight by MacDonagh’s men on Wexford Street and Camden Street. Thereafter, the main action for the Jacob’s garrison was sniping at Portobello Barracks and other military positions which were overlooked by the two towers. Jacob’s was by-passed by the main action as General Lowe decided to concentrate on the GPO and the Four Courts which he considered the more strategically important of the positions held by the insurgents.

News of the surrender did not reach Jacob’s until Sunday. MacDonagh and the garrison surrendered reluctantly. The three most senior officers, MacDonagh, MacBride and O’Hanrahan, were executed.