After McCoy was shot and captured by British Crown forces in 1921, Seán F. Quinn, Pádraig's brother, took over the position.
At the outbreak of the Civil War, the Fourth Northern Division was neutral and in control of the Dundalk military barracks after the British Army vacated it on 13 April 1922.
On 4 July, Aiken wrote to Mulcahy stating the Fourth Northern Division would stay neutral, called for an end to the fighting and for the removal of the Oath of Allegiance from the Treaty because "you have the simple national abhorrence of swearing allegiance to a foreign king and allowing part of the Nation to be ruled by people who have a sworn loyalty to that king.
On 27 July, John McCoy led a small unit that attacked Dundalk, breached the prison wall with dynamite, and in fifteen minutes captured the garrison of 300 men and arms for 400.
A number of escaping divisional members were recaptured by Free State forces, including John McCoy of Mullaghbawn, who had been shot and captured by British Crown forces in 1921, and who had been a brigadier in the barracks before the Free State troops took command.