“World War I” could also have been the Thirty Years War, especially after it merged with the Eighty Years War between Holland and Spain after those countries resumed fighting when a 12-year truce expired. The Dutch and Spaniards clashed in Asia, Mexico and Cuba as well as in Europe, where just about every country from Scandinavia to the Mediterranean was involved.
“World War II” could have been the War of the League of Augsburg (1689-1697); WWIII the War of the Spanish Succession (1701-1714); WWIV the War of the Aurstian Succesion (1740-1748), followed by WWV, the Third Silesian War, Seven Years War, or French and Indian War. In each of these conflicts, fighting took place outside Europe.
You are someone after my own heart.
I would happily debate this subject, and wouldn't mind losing! ;-)
So, here is my opening argument in favor of the Seven Years War (1756 to 1763) being classified as "World War One":
If you can produce a similar looking map for some previous war, I'd like to see it...