The "most shocking single event" of World War II, according to US Secretary of War Henry Stimson, was not the Japanese attack on Pearl Harbor but the fall of France in the spring of 1940. The Nazi invasion of France destabilized Washington's strategic assumptions, resulting in hasty and desperate decision-making. Michael Neilberg offers a dramatic history of America's bewildering response-policies that placed the United States in league with fascism and nearly ruined its alliance with Britain. FDR and his advisors naively believed they could woo Vichy France's decorated wartime leader, Marshal Philippe Pétain, and prevent the country from becoming a formal German ally. The British, convinced that the Vichy government was fully subservient to Nazi Germany, choose to back Charles de Gaulle and actively financed and supported the Resistance. After the war, America's decision to work with the Vichy regime cast a pall over US-French relations that lasted for decades.