On 11/11/1918 World War I’s armistice went into effect.
A good argument is that the European Civil War that was a part of actually ended on 1/1/1999, when Germany and France were united by a common currency.
The only leader who appeared to believe in democracy in World War I was the Austro-Hungarian Emperor Karl the Blessed. World War I helped drive him off his throne.
War is an important tool of policy in a system of international anarchy. But in the 20th century, which saw at its height Hitler, Stalin and Mao, the War that today commerates led to a man who might have been a Saint losing an Empire in the middle of Europe.
Pray for peace.