What is the theme in Birdsong by Sebastian Faulks?

War is a very important theme in Birdsong, and over half of the novel is set during World War I and focuses on Stephen's experiences during the war. Parts 2, 4 and 6 focus nearly exclusively on the war in fact. In France 1916, Stephen is a lieutenant in France during World War I. He feels disdain for his men and even for his best friend, Captain Michael Weir. Stephen refuses all offers of leave, even after he is wounded and nearly dies. A miner in the tunnels on the Front, Jack Firebrace, learns his son has died from a fever and mourns for his dead son. When the platoon is ordered to attack at Hawthorne Ridge, many of them write to their nearest relatives since the attack seems doomed to fail, and Stephen writes to Isabelle because he has no one else to write. Most of Stephen's platoon is killed during the attack.