Totally agree. In the interwar period a strong revenge spirit had developed in Germany after the imposition of the Treaty of Versailles, which meant the acceptance of the defeat of the country in the First World War. The abusive terms of the treaty, which included the demilitarization of the Rhineland, the ban on unification with Austria or the Sudetenland, the loss of German-speaking territories such as Danzig, areas under historical control of the Kingdom of Prussia or Eupen-Malmedy, limitations on the army (Reichswehr), which was reduced to a symbolic military force and the clause that made Germany responsible for the war and with it the obligation to pay heavy tributes in the form of war reparations plunged the German nation, especially after the Great Depression.
To this was added the instability of the political system of the Weimar Republic, since many political sectors rejected its legitimacy. Adolf Hitler's rise to power in 1933 was made possible by the fact that the Nazi movement was able to capitalize on the grievances of German society and based on their ideology began their ambitious demands that included pan-Germanism, the acquisition of "living space" or lebensraum through the conquest of eastern European territories and the elimination of the German and international communist movement.
The ideological tensions in Europe were growing and the instability of the order that emerged from the previous war was increasing. Italy claimed and then conquered Ethiopia in 1935, Japan created a puppet state in Manchuria in 1931, which was expanded with its invasion of China since 1937, and Germany circumvented the limitations imposed in the Treaty of Versailles, secretly began its rearmament, militarized the Rhine region in 1936, joined with Austria in March 1938 and annexed the Sudetenland in October 1938. All these aggressive movements had a weak response from the League of Nations and the old Entente, which opted for a policy of appeasement. In fact, after the Munich Conference where Germany had been allowed to annex the Sudetenland, the British prime minister would say that the agreement ensured "peace for our time." Hitler, however, did not cease in his territorial ambitions, the United Kingdom and France passed to a policy of dissuasion, although with their policy of non-intervention they did nothing to prevent other countries such as Spain after their civil war from passing into the orbit of Germany and Italy.
The Nazis turned their attention to the "Polish corridor" during the summer of 1939, and France and Great Britain pledged to help Poland in case of war. The Nazis made sure to avoid a war with the USSR thanks to the signing of a non-aggression pact, called the Ribbentrop-Molotov Pact, just a week before the invasion. Previously the USSR had tried to establish an alliance with the United Kingdom and France against Germany, but these had rejected it.
Finally, Poland was invaded by Germany on September 1, 1939 and the Allies declared war on Germany on the 3rd. In compliance with the secret Protocol Additional Protocol of the Ribbentrop-Molotov Pact, on September 17, 1939 the Soviet Union invaded Poland. World War II had started.
