Really? TWO world wars? Historians argue that WW1 was the fault of all major powers in Europe then, the masses in France, England, Austria, Russia and Germany cheered when the war broke out. Germany was rather forced into the conflict between Austria and Russia on the Balkans. But maybe you just follow the unjust treaty of Versailles, which said that Germany is the only one to blame (of course, only to make sure that Germany loses much of its power). No, Europe is equally responsible for WW1, and the treaty of Versailles is the reason why the first Republic of Germany (Weimar) failed.
I would have to ask, which country / countries did the surrendering at the end of WW1. That would seem to indicate which country / countries was / were the conquered aggressor/s, regardless of what / who / which nations aligned where and cheered what at the war's inception.
1. Germany under Kaiser Wilhelm was an aggressive militarized autocracy that was accelerating an arms race with England and France to gain greater influence and gain colonies/riches
2. The First World War was ostensibly initiated over the Austro-Hungarian/Serbian troubles but somehow included a massive invasion of France and neutral Belgium.
3. Germany added to the "modernity" of those festivities through brutal and repressive policies of the occupied areas (including summary executions) and the introduction of the flamethrower, poison gasses, the bombing of cities/civilian targets from the air, unrestricted submarine warfare (including the unwarned sinking of passenger liners and hospital ships), etc. And I'm sure that I'm leaving some other jewels out.
The German regime was at fault for the majority of the evil of that war - and to a large degree, the "draconian Versailles Treaty" didn't cause the Second World War; it was the continuation of the militaristic/jingoistic culture of Germany.
It doesn't help a bit to look back on those days and see them through misted glasses; all of us had to learn from them and change our cultures and behaviors.