Let us remember how the setting of this theme clearly links it to one of the most famous violent revolutions in Ireland's history: the Easter Uprising of 1916. The play focuses on one single building and the impact of this Revolution on those individuals inhabiting that building, which serves as a kind of microcosm of the violence on Ireland as a whole.
In addition, you might want to think about how the title of the play refers to the theme of violence. The plough and the stars refers to the flag of the Citizen Army, a leftist movement who formed part of the armed conflict. However, symbolically, we could argue that the title points to a deeper, more ideological conflict, as the plough could be used to refer to human toil and hardship, and the stars refer to idelaism and nationalism. O'Casey was deeply ambivalent about the uprising, as although he admired the courage and zeal of those who fought, at the same time he felt that such action would not change anything and had involved many innocents in the violence. This points towards a major theme of many of O'Casey's dramatic works: the way in which abstract ideals and thoughts can destroy the real life relationships and realities that humans enjoy, as they are pulled into conflicts and violence beyond their understanding or control.