Territorial aggrandizement by Japan in China, by Fascist Italy in Ethiopia, and by Nazi Germany in central and eastern Europe brought the world to war. The League of Nations failed to take decisive action to curb armaments or to stem aggression. The Western powers long pursued policies of neutrality and appeasement — until it became clear that the expansionist nations would not rest content with their gains.

Manchurian Crisis, 1931

At the Washington Conference (1921–22), Japan had concurred in guaranteeing China's territorial integrity and recognizing the Open Door Policy — that the China trade was open to all nations. Despite this pledge, Japan's extreme nationalists looked longingly to the Chinese province of Manchuria, a huge area of great potential wealth. On Sept. 18, 1931, Japanese soldiers stationed in southern Manchuria were involved in a minor clash with Chinese troops. Japan used the incident as an excuse to spread its forces throughout Manchuria, subduing the region by January 1932 and establishing the puppet state of Manchukuo. The League of Nations condemned Japan in 1933 but imposed no sanctions. Japan withdrew from the League.

Hitler Rearms Germany

German chancellor Adolf Hitler abandoned the efforts of his predecessors to ease the provisions of the Versailles Treaty through a policy of reconciliation with the World War I victors. Instead, he unilaterally tore up the treaty. Hitler took Germany out of the League in 1933 and began a massive program to build up the German army, navy, and air force. In March 1935 he restored universal military service. The democracies did not react, and Britain even concluded a naval agreement with Germany in 1935 that permitted greater German naval strength than that allowed by the Versailles Treaty. In 1936, Hitler sent troops into the demilitarized Rhineland.

Conquest of Ethiopia, 1935–36

Italy had unsuccessfully attempted to conquer Ethiopia in 1896. Mussolini, seeking easy foreign victories to galvanize his country, attempted to avenge that still-rankling defeat by sending forces into Ethiopia from Italian Eritrea on Oct. 3, 1935. Another thrust came from Italian Somaliland. Throwing mechanized troops against untrained and poorly armed Ethiopians, the Italians completed the conquest in 1936. With Eritrea and Italian Somaliland, Ethiopia was organized as Italian East Africa. Although the League of Nations imposed an embargo against Italy, it failed to include a vital item, oil, thereby discrediting itself again.

Spanish Civil War, 1936–39

In July 1936 began the Spanish Civil War, a conflict between Spain's liberal-leftist republican coalition government and rightists led by Gen. Francisco Franco. The war soon brought international repercussions. Hitler and Mussolini sent planes, troops, and supplies to Franco, while Soviet dictator Joseph Stalin gave military equipment to the republicans. The United States adhered to a policy of strict neutrality, and Britain and France, anxious to prevent a general war, forbade the shipment of war matériel to the republic. Thousands of anti-Fascist volunteers from Britain and the United States went to Spain, however, to serve with the republicans and were organized with Soviet Comintern aid.

Cooperation between Germany and Italy in Spain helped cement the vague Rome-Berlin Axis, an understanding that they had concluded in 1936. Franco's victory (1939) strengthened Hitler's and Mussolini's positions in the Mediterranean. In 1936 the Japanese concluded the Anti-Comintern Pact with Germany, and a year later Italy joined; this grouping prefigured the later alliance structure of the general war.

Renewal of Japanese Aggression, 1937

A Chinese-Japanese military clash (July 7, 1937) at the Marco Polo Bridge near Beijing (Peking) provided the pretext for an all-out Japanese campaign of conquest in China. By 1939, Japan controlled populous eastern China.

Reacting to events in China, U.S. president Franklin D. Roosevelt spoke in October 1937 of the need to "quarantine the aggressors." A strong negative response to this call indicated the wide extent of isolationist sentiment in the United States. Not until 1940 did Japanese expansionism begin to draw the attention of the American public.

Anschluss With Austria, 1938

Proclaiming the unity of the German people, Hitler from 1934 sought Anschluss ("union") between Germany and his native Austria. In February 1938 he forced Austrian chancellor Kurt von Schuschnigg, under threat of invasion, to admit Nazis into his cabinet. On Mar. 12, 1938, Hitler invaded Austria and incorporated it into his Third Reich.

Czechoslovakia and Appeasement, 1938

Almost immediately afterward, the Nazi regime began agitating on behalf of the Sudeten Germans — who lived in pockets of western Czechoslovakia known as the Sudetenland — claiming that they were a persecuted minority. The Czech government made numerous concessions to the Sudeten Germans, but in September 1938, Hitler demanded the immediate cession of the Sudetenland to Germany. On September 29–30, Britain and France (which was Czechoslovakia's ally) agreed at the Munich Conference to yield to Hitler, who promised to make no further territorial demands in Europe. Czechoslovakia was excluded from participation at Munich. Unlike Austria, Czechoslovakia was democratic, and its president, Eduard BeneÅ¡, was prepared to resist Hitler, but the two western European democracies insisted on submission.

British prime minister Neville Chamberlain hailed the Munich agreement as bringing "peace for our time." In March 1939, however, Hitler destroyed what remained of Czechoslovakia by occupying Bohemia-Moravia and making Slovakia a German protectorate. He also took Memel from Lithuania and began threatening the Polish Corridor, a narrow strip of land that separated East Prussia from the rest of Germany. In the meantime, Italy occupied and annexed (April 1939) Albania.

End of Appeasement, 1939

The Western powers could no longer avoid acknowledging that Hitler's promises were worthless and that his territorial ambitions were not restricted to German-speaking areas but might be limitless. Desperately, Britain and France began to prepare military resistance to Nazi expansionism. In the spring of 1939 they both guaranteed Poland against German aggression. They also sought to begin negotiations with the USSR, whose earlier efforts to form an anti-Axis coalition they had rebuffed.

Stalin, however, had become convinced that Britain and France were conspiring to help throw the full weight of German strength against the USSR. Therefore, despite their bitterly antagonistic ideologies, he sought an accommodation with Hitler. On Aug. 23, 1939, Germany and the USSR signed the 10-year Nazi-Soviet Pact of nonaggression. A secret protocol provided for the division of Poland and the Baltic States between the signatories.

For a delighted Hitler, the treaty meant that he would not have to fight a war on two fronts, because Stalin was giving him the way to move against Poland. Britain and France would be without major allies as they belatedly prepared to defend that beleaguered country.