Tomorrow, Sunday, ends the conflict that has come to define conflict over the last 100 years. Technically, you could almost call this a 100-years War. (Ok, that name has been taken. School in session, see Grim-) But after Sunday, when Germany makes its final reparation payment of 59 1/2 million pounds, all the conditions laid out in the Treaty of Versailles will have been met.
The re-drawing of countries (and the elimination of a few), the debts imposed upon the Central Powers after the war, and the formation of the League of Nations, all led to more warfare later in the century; during the time of WWI, Russia was led into Communism, Ottoman Empire fell, and agencies and taxes begun in the US to run and pay for the war remain to this day. This was really the rise of the Military Industrial Base.
In my mind, the formation of the League of Nations (Later, the UN) will be the undoing of many nations in the coming generations. This may be the most lasting legacy of WW I that we will see.
Go see the article, here, on the real 'end' of the war. To me, WW I was the progenitor of all the troubles we face today.
My grandfather fought in the Great War, receiving injuries that would later get him the Purple Heart on the last day of the War.