With Austria in his grasp, Hitler turned towards the ethnically German Sudetenland region of Czechoslovakia. Since its formation at the end of World War I, Czechoslovakia had been wary of possible German advances. To counter this, they had built an elaborate system of fortifications throughout the mountains of the Sudetenland to block any incursion and formed military alliances with France and the Soviet Union. In 1938, Hitler began supporting paramilitary activity and extremist violence in the Sudetenland. Following the Czechoslovakia's declaration of martial law in the region, Germany immediately demanded that the land be turned over to them.
In response, Great Britain and France mobilized their armies for the first time since World War I. As Europe moved towards war, Mussolini suggested a conference to discuss the future of Czechoslovakia. This was agreed to and the meeting opened in September 1938, at Munich. In the negotiations, Great Britain and France, led by Prime Minister Neville Chamberlain and President Édouard Daladier respectively, followed a policy of appeasement and caved to Hitler's demands in order to avoid war. Signed on September 30, 1938, the Munich Agreement turned over the Sudetenland to Germany in exchange for Germany's promise to make no additional territorial demands.
The Czechs, who had not been invited to conference, were forced to accept the agreement and were warned that if they failed to comply, they would be responsible for any war that resulted. By signing the agreement, the French defaulted on their treaty obligations to Czechoslovakia. Returning to England, Chamberlain claimed to have achieved "peace for our time." The following March, German troops broke the agreement and seized the remainder of Czechoslovakia. Shortly thereafter, Germany entered into a military alliance with Mussolini's Italy.
The Molotov-Ribbentrop Pact
Angered by what he saw as the Western Powers colluding to give Czechoslovakia to Hitler, Josef Stalin worried that a similar thing could occur with the Soviet Union. Though wary, Stalin entered into talks with Britain and France regarding a potential alliance. In the summer of 1939, with the talks stalling, the Soviets began discussions with Nazi Germany regarding the creation of a non-aggression pact. The final document, the Molotov-Ribbentrop Pact, was signed on August 23, and called for the sale of food and oil to Germany and mutual non-aggression. Also included in the pact were secret clauses dividing Eastern Europe into spheres of influence as well as plans for the partition of Poland.
The Invasion of Poland
Since World War I, tensions had existed between Germany and Poland regarding the free city of Danzig and the "Polish Corridor." The latter was a narrow strip of land reaching north to Danzig which provided Poland with access to the sea and separated the province of East Prussia from the rest of Germany. In an effort to resolve these issues and gain Lebensraum for the German people, Hitler began planning the invasion of Poland. Formed after World War I, Poland's army was relatively weak and ill-equipped compared to Germany. To aid in its defense, Poland had formed military alliances with Great Britain and France.
Massing their armies along the Polish border, the Germans staged a fake Polish attack on August 31, 1939. Using this as a pretext for war, German forces flooded across the border the next day. On September 3, Great Britain and France issued an ultimatum to Germany to end the fighting. When no reply was received, both nations declared war.
In Poland, German troops executed a blitzkrieg (lightning war) assault using combining armor and mechanized infantry. This was supported from above by the Luftwaffe, which had gained experience fighting with the fascist Nationalists during the Spanish Civil War (1936-1939). The Poles attempted to counterattack but were defeated at the Battle of Bzura (Sept. 9-19). As the fighting was ending at Bzura, the Soviets, acting on the terms of the Molotov-Ribbentrop Pact, invaded from the east. Under assault from two directions, the Polish defenses crumbled with only isolated cities and areas offering prolonged resistance. By October 1, the country had been completely overrun with some Polish units escaping to Hungary and Romania. During the campaign, Great Britain and France, who were both slow to mobilize, provided little support to their ally.
With the conquest of Poland, the Germans implemented Operation Tannenberg which called for the arrest, detainment, and execution of 61,000 Polish activists, former officers, actors, and intelligentsia. By the end of September, special units known as Einsatzgruppen had killed over 20,000 Poles. In the east, the Soviets also committed numerous atrocities, including the murder of prisoners of war, as they advanced. The following year, the Soviets executed between 15,000-22,000 Polish POWs and citizens in the Katyn Forest on Stalin's orders.World War II 101 | Next: The Phoney War to the Battle of Britain