One interesting part of World War I history is the US refusal to formally end the war with Germany until 1921. Wanting to return to its isolation from world conflicts, the US refused to ratify the Treaty of Versailles, which would have made the US a member of the League of Nations. This meant that the US and Germany were technically still at war until July 2nd, 1921, when the Knox-Porter Resolution was signed.
Although President Woodrow Wilson was one of the strongest advocates for the creation of a League of Nations, the republican senate, led by Henry Cabot Lodge and William Borah, refused to join it. This left the US and Germany in diplomatic limbo. The US Senate voted against ratifying the Treaty of Versailles in 1919 and 1920, and in 1921 President Warren G. Harding spoke against the treaty. It thus fell to Congress to create a peace resolution. The House and the Senate each came up with their own resolution, and it took a few weeks to reconcile the two and finally pass the result on July 1st. The next day, while golfing at the Frelinghuysen estate, Harding signed the resolution, ending the war with Germany.
While the Knox-Porter Resolution may not have been a critical moment in history, I think that it provides an interesting insight into the way that international diplomacy works. That a war can officially continue for more than two years after fighting stops because a nation’s legislative body refuses to ratify a treaty shows just how great an influence domestic politics have on international ones. Further, the refusal of the US to join the League of Nations, which forced it to create the Knox-Porter Resolution as an improvised solution, would have a destabilizing effect on the world in the following decades.