Repeatedly throughout his declaration of intent known as Mein Kampf, or My Struggle, a young, imprisoned Adolf Hitler, who had served in the German Army during the Great War (later to be known as World War I, it not being logical to name the first war with a digit when the second conflict had yet to occur) and who had witnessed his nation's humiliation at the hands of the Great War's victors, namely, Britain and France, refers to the Treaty of Versailles, the agreement under which Germany was forced to pay for the sin of losing. These references are not kind, yet they represented the perspective of many Germans who had grown exhausted by their requirement under the treaty's terms to pay reparations to the victors, to refrain from rebuilding their military, and to admit to being the cause of the greatest war in European history. As Hitler wrote in one such passage:
"Our nation which has to exist disarmed, under the thousand eyes appointed by the Versailles Peace Treaty, cannot make any technical preparations for the recovery of its freedom and human independence until the whole army of spies employed within the country is cut down to those few whose inborn baseness would lead them to betray anything and everything for the proverbial thirty pieces of silver."
Hitler's bitterness and determination to avenge Germany's treatment at the hands of the war's victors would prove a major contributing factor in the even-more destructive conflict that would come. And, it is here that one finds the answer to the question "Why is the end of World War I viewed as a cause of World War II." The Treaty of Versailles, as noted, set forth conditions on Germany that were viewed then (by Germans) and are viewed by some analysts today as unfair. Those conditions included the prohibition on rearming except for very limited purposes; the forced payment of reparations to the victors, a particularly difficult burden for a country already decimated by war and by the depression that had swept the globe; the requirement that it accept blame for the war's beginning despite the failures of the victorious countries to pursue policies that would have prevented war; the loss of considerable territories Germany was forced to relinquish to the victors; and the occupation of Germany's most important industrial region, the Saar, by the League of Nations.
Whether a more magnanimous approach by the Entente towards the defeated Germany would have prevented World War II will never be known with any certainty. What is known, though, is that millions of Germans viewed the terms of surrender as excessively harsh and as intended to humiliate them. Hitler was able to exploit his countrymen's bitterness during his ascent to power, and successfully played on their fears of international conspiracies designed to keep Germany in a weakened state. It is safe to conclude that the end of World War I facilitated the emergence of World War II.