While the book deals with the horrific experiences of a soldier severely wounded in World War I, the character of Johnny is entirely fictional.
However, Trumbo drew inspiration from the experiences of real soldiers he encountered during his time as a journalist and screenwriter. He also used his own experiences in World War I to inform the novel's themes of pacifism and the horrors of war.
While the story isn't true, it effectively captures the devastating impact of war on individuals and society, making it a powerful and impactful read.