Many people of the 1920s and 1930s referred to World War I as the “war to end all wars.” But the vindictive terms of the Treaty of Versailles that ended World War I, in concert with the international depression of the 1930s, actually created the circumstances that led to World War II. In Germany, the harshly punitive Treaty of Versailles provoked intense bitterness and resentment. These feelings of anger and despair paved the way for the charismatic demagogue Adolph Hitler to take power in Germany and install a fascist regime in 1933. Eleven years earlier, a fascist regime had risen to power in Italy under Benito Mussolini. These two fascist governments combined their extreme nationalist rhetoric with an aggressive desire to expand.

In October 1935, Italian forces invaded Ethiopia, gaining control of the African nation by May 1936. Also in 1935, Hitler announced plans for German troops to re-occupy the Rhineland, which had been demilitarized by the Treaty of Versailles. Troops marched into the Rhineland unopposed in March 1936. Germany and Italy formed an alliance, the Rome-Berlin Axis, in October 1936. In March 1938, Austria joined this alliance when Hitler announced the Anschluss, a union between Germany and Austria, and German forces marched into Vienna. When Hitler declared his intention to take the Czech Sudetenland by force if necessary, British and French leaders acceded to his demands, signing the Munich Pact in September 1938, which granted the Sudetenland to Germany in an attempt to appease Hitler and avoid war.

Germany, however, did not cease its expansionary actions: German troops invaded Czechoslovakia in March 1939 and Poland in September 1939. Two days after the invasion of Poland, Britain and France declared war on Germany, honoring their treaty with Poland.

In the mid-1930s, mired in the Depression, the U.S. focused on its own problems. Isolationism and antiwar sentiments ran high. A series of Neutrality Acts, passed between 1935 and 1937, reflected these isolationist currents. The acts made arms sales to warring countries illegal and forbade American citizens to travel aboard the ships of belligerent nations. President Franklin Delano Roosevelt supported the neutrality acts only half-heartedly but found it impossible to fight the will of the majority and urge U.S. involvement in international affairs. FDR did succeed in helping to defeat the 1938 proposal for a constitutional amendment, the Ludlow Amendment, which would have required a national referendum on any declaration of war not sparked by a direct attack.

In this atmosphere of isolationism, American response to the rise of fascist states in Germany and Italy was limited and weak. During most of the 1930s, few Americans saw Adolph Hitler and Benito Mussolini as dangerous. FDR urged negotiations with Hitler, but never openly advocated military action before the late 1930s. He suggested a plan to “quarantine” the aggressor nations in Europe in 1937, but the plan received little public support.

The only sign of wavering in America’s isolationism during the early and mid-1930s was its involvement in China. In 1931, Japan invaded the Chinese province of Manchuria and in 1937 began launching attacks on the remainder of China as part of its aim to build an Asian empire. Alarmed that Japan’s aggressive expansionism might threaten U.S. holdings in the Pacific, if not the U.S. itself, the U.S. refused to recognize the Japanese government in Manchuria. In 1937, the U.S. extended loans to China and urged a boycott of Japanese silk.

American public opinion began to turn against the fascist powers during the late 1930s, mostly in response to the publicized brutality of Hitler’s Nazis toward German Jews and other groups. Nonetheless, many Americans continued to push for neutrality and for immigration restriction, in part because roughly 60,000 Jewish refugees fled to the U.S. between 1933 and 1938.

In early 1939, FDR asked Congress to appropriate funds for a military buildup and an increased production of military material. In September 1939, FDR succeeded in pushing Congress to revise the Neutrality Acts to allow warring nations to purchase arms from the U.S. as long as they paid in cash and carried the arms away on their own ships. This cash-and-carry provision appealed to a nation that was increasingly committed to aiding the Allied war effort but did not want to get directly involved.

Opposition to war continued to fade as Hitler’s troops invaded and conquered Denmark and Norway in April 1940, Belgium and the Netherlands in May, and France in June, followed by the Battle of Britain throughout the summer and fall, in which German planes bombed British cities.

In this atmosphere of growing alarm, FDR decided to run for an unprecedented third term in office. (George Washington had established the convention that no president serve more than two terms in office, which every president until FDR had followed.) During his 1940 campaign, Roosevelt appointed a Council of National Defense to oversee defense production, appointed Republican Henry Stimson secretary of war, and approved a peacetime draft by signing the Selective Service and Training Act. Although he approved the draft, FDR pledged never to “send an American boy to fight in a European war.” Isolationists opposed to FDR’s reelection sponsored the Committee to Defend America First, urging neutrality and claiming that the U.S. could stand alone regardless of Hitler’s advances in Europe. FDR won reelection in spite of the committee’s efforts.