The representation of violence in The Wars is paradoxical in that violence is given to the reader as both a source of chaos and order.
In terms of chaos, the violence of the First World War, supposedly the war to end all wars, generates a considerable amount as millions of people are sent to their deaths, nations are torn apart, and families are devastated by loss.
Yet violence, as depicted in the novel, is also a source of relative order and stability, as we discover when Robert uses his pistol to impose much-needed discipline on his men in the middle of a deadly gas attack. Here we see the violence of the gas attack, which generates panic and chaos, as well as the violence of the pistol that brings order out of chaos.
Robert's use of violence, however, also tends toward chaos in his challenging the existing military hierarchy by the shooting of Captain Leather. Although Robert could well plead self-defense, there's little doubt that his superiors would not see his actions in such an indulgent light. On the contrary, they would undoubtedly see Robert's killing of Leather as an act of gross insubordination prejudicial to good discipline.