MacBride's participation in the violent events which shook Ireland from 1919 onwards formed the basis of his political and personal identity in the years that followed. Within post-Treaty IRA circles, MacBride was certainly regarded as ’having the well-deserved reputation of having a good IRA record’, despite his relative youth. A recent publication notes that by current standards, MacBride would be ‘stigmatised as a child soldier … and his recruiters would be guilty of war crimes’. MacBride's revolution was somewhat slow to start, however. His schooling in Wexford removed him from much of the early activities of the Dublin IRA; and when he did return and join their ranks, it was as a very junior member. In so far as MacBride's revolution can be held as emblematic of anything, it is the revolution of an adolescent, desperately eager to please, who achieved middle rank and was involved in a respectable number of ambushes without achieving the fame of a Dan Breen or an Ernie O'Malley. Indeed, such an experience is arguably the more commonplace for Ireland's revolutionary heroes. MacBride's story from 1919 to 1921 is that of a young man trying to find a place for himself in the country and the circumstances he had been brought up to consider his birthright: fighting the British in Ireland.

The initial stages of what came to be known as the War of Independence rather passed MacBride by. While he was at school in Wexford, events elsewhere were assuming a momentum of their own: the inaugural meeting of Dáil Éireann in January 1919 was given an unexpected resonance by the murder of two policemen the same day in County Tipperary. This, however, is not to suggest that the republican leadership in Dublin had ordered or even sanctioned the attack. The new Dáil government pinned the majority of its hopes on securing international support for the reaffirmed Republic of Ireland. Business during its early sessions – MacBride attended the third sitting, on 10 April – included an appeal for recognition from (and admission to) the Paris Peace Conference.

The reconstruction of MacBride's movements during the early stages of the revolutionary period poses definite challenges, among these his failure to provide a witness statement to the Bureau of Military History.