In March 1918, after the Germans had displayed their strength in a series of successful offensives, Foch became supreme commander of the Allied armies. Charged with keeping them intact and holding back the Germans, he drew on a lifetime's experience as a soldier. In 1871, he joined the French army at 20, attended a war college and eventually became an instructor there. Forced out of retirement, he became a key French figure in World War I. In August 1918, Foch was named marshal of France.