A hero of World War I, known for applying the lessons of the Second Battle of Champagne to minimize casualties in the Battle of Verdun, Pétain became commander of French forces in 1917. He came to power in World War II as a reaction to the stunning defeat of France in early 1940. Pétain blamed a lack of men and material for the defeat, but had himself participated in the egregious miscalculations that led to the Maginot Line, and the belief that the Ardennes were impenetrable. Nonetheless Pétain's cautious and defensive tactics at Verdun had won him acclaim from a devastated military, and poet Paul Valéry called him "the champion of France."