During World War I, Monnet held various positions in the Allied purchasing, shipping, and supply bureaucracy. From 1919 to 1922 he was deputy secretary-general to the new League of Nations and was instrumental in organizing an international loan that facilitated Austrian postwar economic reconstruction. From 1923 until the late 1930s, he was a partner in various American financial firms, raising further international European reconstruction loans in the 1920s and attempting to do the same in China for much of the 1930s.
An early opponent of Adolf Hitler, from the 1938 Munich Agreement until the defeat of France in June 1940 Monnet sought to facilitate major French armaments purchases in the United States. After the fall of France, he unobtrusively became a key member of the Washington-based British Supply Commission, relentlessly lobbying President Franklin D. Roosevelt and his administration for sharp increases in industrial war production and enormously expanded aid to Great Britain. Monnet spent most of 1943 in Algiers helping to organize a united front for France's liberation including both Vichy and Gaullist Free French forces, an organization that General Charles de Gaulle soon dominated. Monnet returned to the United States in October 1943 as France's commissioner-at-large to negotiate presidential recognition of de Gaulle's position, a formal Lend-Lease agreement, and relief and reconstruction aid for liberated France.
Returning to France in November 1945, as commissioner general for planning Monnet speedily devised the Monnet Plan for French economic revival and modernization, a program driven by a mixture of democratic planning and foreign economic assistance. Convinced that only full-scale European cooperation would prevent future devastating wars, from 1945 onward he quietly but relentlessly crusaded for this, playing central roles in the establishment in 1951 of the ECSC, of which he became the first president, and its 1957 successor the European Economic Community (EEC), which ultimately evolved into the European Union (EU). Monnet's longstanding friendships with key American officials including John Foster Dulles, John J. McCloy, George W. Ball, and numerous others helped him to win American support for these endeavors. From 1955 Monnet, universally considered the preeminent founder of a unified Europe, headed the Action Committee for the United States of Europe, working constantly to strengthen existing institutions. Monnet died at Montfort-l'Amaury, Yuelines, Ile de France, on 16 March 1979.
Duchêne, François. Jean Monnet: The First Statesman of Interdependence. New York: Norton, 1994.; Hackett, Clifford P., ed. Monnet and the Americans: The Father of a United Europe and His Supporters. Washington, DC: Jean Monnet Council, 1995.; Monnet, Jean. Memoirs. Garden City, NY: Doubleday, 1978.; Roussel, Eric. Jean Monnet, 1888–1979. Paris: Fayard, 1996.