"Casualty" deals with the poet's reaction to the killing of 13 civil rights protest marchers by British troops in 1972 in Derry. This event is referred to as "Bloody Sunday" or the "Bogside Massacre." The march was conducted by the Northern Ireland Civil Rights Association seeking to strengthen rights of the Catholic minority in Northern Ireland.
In the first stanza, the poet describes one of the subjects who would be killed. The poet describes the subject with great admiration, saying he was unemployed (dole-kept) but a hard worker, calm and collected at the bar. The poet would shift the conversation from poetry to other things if he felt it would be more magnanimous. The poet recalls this in the final stanza with some regret since he would like to have this conversation again.
The first stanza expresses the poet's feeling and plea for solidarity. The simplicity of the language and the shortness of the lines come across as very straight forward; the admiration of those killed and the significance of their commemoration in this poem do not require lofty prose. The simplest expression of these events is significant and moving enough.
In the second stanza, the poet compares the coffin procession to innocent images such as "blossoms on slow water." This procession is written as a natural flow from the description of the poet's anonymous subject's calm demeanor at the bar. However, disrupting that flow to acknowledge the violence, he then imagines seeing the subject's face, still full of life just before the gun shots. The poet then describes him as a fish swimming up to the light of the bar, more water imagery, which is a very subtle way of conflating the subject with natural or even supernatural (becoming other animals in nature) phenomena. It's as if nature itself is asking the poet "why the violence?"
The poet missed his funeral but finds himself on a boat carrying the coffin or he imagines this.
I was taken in his boat,
The Screw purling, turning
Indolent fathoms white,
I tasted freedom with him.
The line breaks in the last stanza are also short and rhythmic like the waves or the way the boat slowly plods out to sea. The escape from the land symbolizes a temporary escape from the "troubles" (the political conflicts in Ireland), temporary meaning just long enough to honor the dead. The poet ends by asking the subject (revenant meaning "to return") to come back and ask him the question again. By focusing on this one, anonymous victim, the poet witnesses a more personal, intimate affection. Put into context with the social significance and the other victims, this puts a more subjective face (even if anonymous) on the victims of what are usually dispassionately described as the casualties of war and political struggle.