WW1 was also known as The Great War or World War I (only after the Americans fought in WW2 and they started a re-branding exercise and renamed it with roman numerals). It involved all the great world powers (not the great unworldly powers like electricity, gravity, momentum, or the IRS), and there were teams.
To keep it simple we’ll call them the Centrals and the Allies. Who would want to join the Centrals when you could be on the Allies? Surely the opposite of Allies is Enemies, so who would America join – us or them?
So Woodrow Wilson (ironically also earning the moniker WW) spent a few years keeping the US out of the war finally jumped in with two feet and decided to put the boot in to the enemies:
- Germany
- Austria-Hungary aka Arnold’s family tree
- The Ottoman Empire aka Turkey
- Bulgaria