Everybody knows that World War II began once on 01 September 1939, the German Army crossed The Polish border and attacked Poland. Subsequent to the guarantees given by the UK and France to Poland, they declared war on Germany. This is the physical aspect of the war, but in reality the seeds of the Second World War lay in the aftermath of the First World War (1914-18).
During the First World War, the Allies had defeated Germany and at the end of the war, as victors the treaty of Versailles was signed in 1919. This treaty imposed humiliating terms on the Germans and severe restrictions were put on Germany as far as war material and air craft was concerned. In addition Germany was imposed a financial burden that was beyond the capability of the German nation.
The allies also took away all German colonies in Africa and imposed restrictions on the size of the German armed forces. Germany was also denied further research in most fields and the situation reached such an impasse that that the engine used to power the Zeppelin (Air Ship) was used to power the Maybach car! All this resulted in high inflation and German economy sank like a large stone in a pond.
The result was that discontent among the people grew in Germany and they were open to anybody who could lead them to self respect and a better life. In such a situation Adolf Hitler appeared on the scene like a Godsend and he began to address the German problems by his own methods, through flamboyant speeches backed by skill full oratory. The depressed masses saw in Hitler a savior, who could lift them from their moribund existence and hence they voted for him in large numbers. Thus in real terms Hitler who became a dictator was initially voted to power through the ballot. There is no denying that. Perhaps if the German economy was vibrant and the humiliating terms of the Versailles treaty watered down, Hitler may have found it difficult to sweep himself into power.
Thus the seeds of the Second World War are there in the treaty of Versailles. It is no coincidence that after the defeat of France, Hitler sat in the same carriage where the earlier treaty was signed and dictated humiliating terms of surrender to the French. When Hitler clause by clause abrogated the treaty of Versailles he became a hero in the eyes of the common German man. No doubt, there were other complimentary reasons like the sell out at Munich (1938), but in real terms the origin of the second war lies in the end of the first war and the treaty of Versailles.