The gradual incline of the support for Nazism and Hitler, during the 1930's in particular, can be said to be the result of several factors - those within the control of Hitler and the ones outside of his power, although he was often able to manipulate these to his advantage. I believe that such external issues played a great role in propelling Hitler to the forefront of German politics, a process which may have been otherwise drawn out or possibly unsuccessful, it was these factors that gave the Nazi Movement the opportunities it needed.
The Nazis were born out of the aftermath of World War One into a country seriously damaged by the demands of the Treaty of Versailles. Germany had been split in two, loosing 13 percent of its population - half of whom were ethnic Germans. The country lost vast amounts of raw materials and land, were banned from having an air force and U-Boats, and were forced to pay reparations to the Allies as compensation for the War.
The Treaty of Versailles systematically denied German people their National Rights and left many angry at the new democracy (the Weimar Republic) that had signed the agreement. This armistice was a key factor in the support for Hitler as many people felt betrayed by their Government for allowing such restrictive measures on their homeland. Hitler and the Nazis offered a return to the once powerful country of Germany, denying the Treaty of Versailles and leaving behind the weaknesses of the Weimar Republic.
Democracy was introduced towards the end of World of War One as the threat of invasion left the Kaiser (the King of the Second Reich) open to radical ideas and persuasion. He was eventually convinced to hand over power to a civilian government - transforming the Reich...