The only one that matters is 1918. Otherwise we would all be playing Die Alten Schriftrollen and have no say in whether our government invades another one's country..
I'm sorry, I know this is off topic, but that statement is wrong in so many ways. The idea that "we would all" have been taken over by Germany (assuming that includes the United States) is ludicrous. WWI was not a war of world domination - it was an war between two more-or-less equal European alliances. It was a useless, wasteful endeavor. This was not good guys vs. bad guys, it was just plain idiocy, a complete failure of the alliance system. Second, none of the major powers (except the US) had a say as to whether their country got involved in it - both sides had a series of treaties requiring them to go to war if one of their alliance was attacked, so when the first declaration started, all the various countries automatically were at war. Finally, the idea that we now have a say in whether our country invades another country is pretty funny. The US is currently bombing 5 countries at least - I don't recall being asked about that.