Heaney's "Casualty" is an elegy that follows the traditional elegiac format in that it is divided into three sections. The first, as in a traditional elegy, is a lament for the dead person. The third section, also traditional, is an expression of consolation. It is arguable, however, how far the second section offers praise for the "idealized dead." Indeed, the subject of this poem is not described as ideal in any way; he is an individual the speaker cannot quite define. The speaker knows his subject's motivations and inclinations, but the process of analyzing or evaluating them remains a "puzzle" to him. It is not really defined whether the subject is a good person or if his reactions to the conflict around him are good reactions.

The imagery in Heaney's poem is fairly consistent throughout. The "casualty," a fisherman, has deliberately "turned his observant back" on what is around him and rejects curfews and warnings in order to pursue his goal of drinking "like a fish." The progression of this fish and water imagery is fascinating. It is like the fisherman is trying to find a sense of belonging in drinking, as if this might transform him into a fish himself—thereby helping him find his way back to his "proper haunt." The final section of the poem offers a serene image of consolation: the fisherman and the speaker out in a boat, a "rhythm" taking them home. Here, too, there is "purling, turning," and there is nothing going in one consistent direction. Far from pointing the reader towards a final and definite answer, Heaney simply offers more questions. Even the dead man is pictured returning as a "revenant," and the speaker wishes he would "question [him] again."

The fisherman is of course not the only victim of what has happened to him. There were "thirteen men" killed in Derry, but the poem suggests that the fisherman is different in that his motivations are different—he is not part of "our tribe's complicity." The speaker is wracked by the question of whether the fisherman is in any way "culpable" in his own death. Why was he there? Was he simply pursuing his desire to be out "drinking in a curfew"? Was this simply his way of wrestling with the sense of being out of place—Irish, English-speaking, Catholic, Protestant—while others took to their "tribes" and engaged in a conflict mediated by British soldiers?

Ultimately, Heaney's poem raises more questions than it answers. The reader is left with the strong sense that the speaker is still "purling, turning," and questioning himself.