Which nation did NOT fight alongside the Allied Powers during World War I?

World War I, a massive conflict that reshaped the 20th century, saw Europe and the world divided into two major alliances: the Allied Powers and the Central Powers. The Allied Powers, also known as the Entente, were primarily Great Britain, France, Russia (until 1917), Italy (from 1915), the United States (from 1917), and Serbia. These nations joined forces to combat the aggression of the Central Powers. Now, Bulgaria actually sided with the Central Powers, which included Germany, Austria-Hungary, and the Ottoman Empire. Bulgaria's motivation stemmed from territorial disputes in the Balkans and a desire to regain land lost in previous conflicts. So, while Italy, the USA, and Serbia were all fighting *for* the Allied Powers, Bulgaria was actively fighting *against* them, making it the nation that did *not* fight alongside the Allies. It's easy to get confused with the shifting alliances of the time, but remembering Bulgaria as part of the Central Powers helps clarify their role in the war.