One hundred years after the start of World War I, it is still extremely difficult to comprehend just how global a phenomenon the war was. It affected people on every continent, and hastened the end of the European empires.
Reddit user Srirachachacha shared this map showing the amazing spread of the war across the world. The GIF does a fascinating job of distinguishing between the key Allied and Central Powers and their colonies, dominions, and territories.
World War I started off solely as a military conflict between the Austro-Hungarian Empire and Serbia following the killing of Austro-Hungarian Archduke Franz Ferdinand by a Serbian assassin. Through a web of entangling defensive alliances, the conflict quickly morphed into a war that pulled in almost the entirety of the world.
By the time the war ended, the Russian, Ottoman, Austro-Hungarian, and Prussian Empires had collapsed. The war claimed over 37 million lives, and large swathes of Europe lay in complete destruction.
Incredibly, only two decades later the world would be poised on the brink of World War II.