As the title of Lines of Courage suggests, Nielsen’s novel explores different ways courage is found by its characters. Throughout her story, each of the main characters faces adversity brought on by the war, and their actions in the face of danger and injustice define their courage. As this book falls into the middle grade fiction genre, all the protagonists are teenagers, and the novel charts their coming-of-age alongside their development of courage.

This courage takes a different form for each character, but it is always accompanied by the awarding of Sergeant Baum’s Golden Cross of Merit, which Nielsen employs as a symbol marking bravery. Felix must overcome his guilt and shame to become a war hero; Kara must listen to her own moral compass when saving lives; Juliette must overcome loneliness and obstacles without giving up; Felix must endure the tragedy of war and loss before he can find peace; Elsa must reevaluate her loyalty to her country and recognize injustice.

In short, the narrative emphasizes the importance of small, individual acts of peaceful heroism guided by personal morality over patriotic violence. Additionally, it suggests that courage is developed through adversity, rather than being an innate quality.