The Battle of Verdun, which lasted from 21 February to 15 December 1916, was a turning point in the First World War and Fort Douaumont was the heart of the battle. Situated at 395 metres above sea level, Fort Douaumont was in 1914 the strongest and most modern of the forts around Verdun. It formed the keystone to the French defence around the city and its possession allowed for unrivalled observation over the whole sector. Using both French and German sources this book introduces the reader to the fortress system around Verdun, explains the construction, reinforcement and armament of the fort and describes its surprise capture by the Germans in February 1916. The terrible blow to French morale caused by the loss of the strategically important fort, their attempts to retake it and the conditions of life inside are portrayed in detail. As the months ground on and the Battle of Verdun turned into stalemate, the desire to keep or to recapture Fort Douaumont, whatever the cost, became the reason for both sides to go on fighting. During their eight-month period of occupation, the Germans took steps to render the fort impregnable and following its successful recapture by the French in October 1916, further defensive work was undertaken that clearly foreshadowed the development of the Maginot Line forts with their machine rooms, workshops, deep tunnel systems and specialized personnel.