I personally disagree with calling WWI and WWII one whole war, but you could legitimately argue that WWI left nothing resolved and that the subsequent peace treaty (i.e. Treaty of Versailles), which intended to cripple Germany economically and militarily, only strengthened the German people's resiliance and bitterness towards the Western Powers, particularly France. Despite marginal attempts at international cooperation in the 1920s, such as the Dawes Plan and the Locarno agreements, the political atmosphere in Europe was harbored with animosity by everyday Germans, plaqued with hyperinflation and unemployment, towards the French. The French occupation of the Ruhr in 1923 and their construction of the Maginot Line indicated that this same resentment was harboured by the French as well. To top it all off, the very Weimar Republic of Germany, that negotiated the Locarno Agreements with the Western powers (France included), was a highly unpopular one with the German people. Therefore, you could argue that Germany by the early 1930s was ripe for a government that would revigorate German dreams for a revamped German Empire, and a reconstructed military that would one day set its sights on the conquest of its enemies. That type of government, of course, would be the Nazi Party - and much of Hitler's success in seizing power and rebuilding the German Empire was due in large part to his condemnation of the Treaty of Versailles as being the very treaty that precipitated Germany economic crisis in the 1920s. This analysis does look only at Germany's role in Interwar Period, which is why I don't like to label WWI and WWII as "one big war," but that is what you could argue if you were to make that call...