I think that World War I should be called a "world war" because it was faught in more than just Europe.   In China, India, Australia, Indonesia, South America, Africa, and the Pacific Ocean, Germans and British were fighting to gain or protect land and economic growth.  The Germans even had a plan to attack the east coast of the United States.  This would have brought the war to our very front door.  And given the fact that they sent 60 warships and about 100,000 men,  it sounds like it would have been more of an invasion that, I believe, we probably would not have been able to fight off.