Following the outbreak of the First World War in August 1914, the Irish Republican Brotherhood decided to stage an insurrection at the next opportune moment, bearing in mind the maxim of England’s difficulty being Ireland’s opportunity. In May 1915 it established a military committee (later the Military Council) consisting of Patrick Pearse, Joseph Plunkett and Éamonn Ceannt, all IRB men but appointed primarily because they held senior positions in the Irish Volunteers. Later that year, the Military Council was expanded by the addition of Seán MacDiarmada and Tom Clarke. The Military Council was particularly concerned with the procurement of arms. In this respect, it would appear that it placed too much reliance on Sir Roger Casement’s proposed shipment from Germany.

In January 1916 the Military Council agreed with James Connolly, who was not a member of the IRB, to mount a joint insurrection by members of the Irish Volunteers and the Irish Citizen Army. Connolly was then co-opted to the Military Council. A seventh member was co-opted in early April: Thomas MacDonagh, a member of the IRB and commandant of the 2nd Battalion of the Dublin Brigade of the Irish Volunteers. When Easter Sunday was designated as the day for the insurrection, Pearse as director of military operations ordered that all Volunteers gather at their assembly points throughout the country on Easter Sunday for three days of field manoeuvres.

It was decided that the seven members of the Military Council would constitute the Provisional Government of the Irish Republic. They agreed the content of the Proclamation to which Pearse, Connolly and MacDonagh were the main contributors, Pearse being entrusted with the drafting. With the exclusion of Plunkett who was in hospital, they met shortly before Easter at the home of Mrs Jennie Wyse-Power in Henry Street where they finalised and signed the Proclamation.

Well aware that previous attempts at revolution had been stymied by leaks, spies and informers, the Military Council managed to keep its plans secret to the extent that neither the head of the IRB, Denis McCullough, nor the head of the Irish Volunteers, Eoin MacNeill, knew that the manoeuvres were intended as cover for an insurrection. MacNeill, however, found out on Easter Thursday and countermanded Pearse’s order for manoeuvres as he felt that the Volunteers were not yet ready for such a momentous undertaking. When told, however, that a German ship was about to land a cargo of arms in Co. Kerry and that the British were preparing to suppress the Volunteers, he withdrew the countermand.

The German ship Aud carrying the arms arrived off the Kerry coast on Holy Thursday, but due to a failure of communications it failed to make contact with the local Volunteers and was eventually scuttled by the captain. When it became known on Holy Saturday that Casement had been arrested and that the arms were lost, MacNeill definitively countermanded Pearse’s order for the Easter manoeuvres. Early on Sunday, the Military Council met in Liberty Hall to consider the implications of MacNeill’s countermand which had appeared that morning in the Sunday Independent. They decided to postpone the Rising until noon the following day, Easter Monday, to enable them to notify the Volunteers throughout the country that the Rising was indeed taking place. The Proclamation was printed that day on the printing press in Liberty Hall.