The Wars

This is largely a thematic question of which there are a few. Much of the novel concerns Robert's loss or destruction of Innocence. 

As the novel progresses several innocent figures are consumed by the war. This begins with Rowena's death, a tragic accident due to Robert's shirked responsibility. It is visited again after Robert shoots the horse aboard the ship. He has been forced to commit an act he detests. Findley also comments on the age of the men on board going to war to draw attention to their boyish innocence. They are barely men at all.

Robert isn't the only character whose innocence is lost. Juliet is forced to grow up quickly after seeing Robert and Barbara having sex. This incident also evokes the theme of change that appears in the novel. Rodwell, too, loses his innocence and takes his life as a result. He is driven to suicide after watching his fellow soldiers kill a cat just to taunt him. The destruction of the natural world and animals is also an example of the destruction of innocence.