O’Casey shows the horrors of war through the tragic effect of Ireland's Civil War on ordinary families.
The action of the play is entirely within a domestic setting, but the impact of the war is devastating. Two mothers lose their sons.
Through the grief expressed by these women, O’Casey shows that death is horrific regardless of how worthy the cause may seem.
Again, we see this attitude in one of his other plays in the Dublin trilogy.
In The Plough and the Stars, Nora Clitheroe asserts that “There’s no woman gives a son or a husband to be killed - if they say it, they’re lyin’, lyin’, against God, Nature, an’ against themselves!”
This also seems to show O’Casey’s belief that no one gladly gave their lives or the lives of loved ones for any cause.
The brutal murders of Robbie Tancred and Johnny Boyle, along with the effects those deaths have on their families, demonstrate the futility of the war.
O'Casey shows that there is not much support for the families affected. The Irish police are of little help, as Mrs Madigan asserts, "For you're the same as yous were undher the British Government - never where yous are wanted! As far as I can see, the Polis as Polis, in this city, is Null an' Void!".
O'Casey draws on his experience of living through these events and shows that those who feel it is their duty to fight for their country are rarely given any thanks or reward, especially the working classes.
The constant fear and psychological trauma Johnny experiences throughout the play - a fear we come to realise is not irrational but understandable - shows the consequences for many of those who contributed to the nationalist cause, even if they did survive.