Having devised the plan, in December 1939 he participated in the IRA's Dublin Brigade raid of the Irish Army Magazine Fort in the Phoenix Park, when the entire stock of the Irish Army's ammunition was seized, a quantity of just over one million rounds, and removed in a dozen lorries.
In 1940, he acted as adjutant general to Stephen Hayes, IRA chief of staff.
As part of the IRA's restructuring following World War II, the organisation resolved that they should add a political dimension to their previously strictly military only outlook.
By the late 1940s Sinn Féin was a shadow of its former heights, and it did not take long for the IRA to subjugate the party.
Ó Dubhghaill was picked by the IRA to be one of those who would now publicly control Sinn Féin.