The frustration–aggression hypothesis has largely been ignored in scholarly literature regarding the examination of political elites. We investigate this hypothesis through a quantitative operational code and historical analysis of the Irish 1916 Easter Rising against the United Kingdom. The article looks at the effect of frustration levels of rebel leaders James Connolly, head of the Irish Citizen Army, and Patrick Pearse, leader of the Irish volunteers. Findings show that both leaders were frustrated, particularly Pearse, whose policies changed from peace to violence over a four-year period that coincided with a rise in his level of frustration. The findings in this paper support the frustration–aggression hypothesis, and may provide insights into aggressive actions by state actors, malcontents, and leaders of the oppressed.