Gamelin, Maurice Gustave, 1872-1958, French army officer. During World War I he served on General Joffre's staff and as a division commander. He was made chief of the French general staff (1931) and chief of staff of national defense (1938). When World War II broke out, he commanded the Allied forces. Considering France ill prepared for war, he relied on the Maginot Line and on passive warfare. In May, 1940, Germany began to overrun France; on May 19, Gamelin was replaced by Gen. Maxime Weygand. Arrested by the Vichy government, Gamelin was a defendant at the abortive trial at Riom. He was freed from imprisonment in Germany in 1945.