World War I: The Great War

This war was known as the "Great War" not just because of the millions of people involved and affected by it, but because of it's size. It was a huge war, involving a large number of nations and armies, including five empires with their associated colonies and states. 
World War I was a military conflict lasting from 1914 to 1918. One of the major causes of this war was the assassination of Archduke Franz Ferdinand of Austria by a Serbian nationalist in 1914. This war involved and focused on two opposing powers. The Allied powers, which consisted of Great Britian, France, Russia, Italy and eventually, The United States versus The Central Powers, which consisted of Germany, Austria-Hungary, The Ottoman Empire and Bulgaria. 
Trench warfare, as well as machine weapons, tanks, and chemical warfare was introduced during this war. 
This war had been known as, "The War to End All Wars." The war officially ended in November 11th, 1918 with the signing of an armistice between Germany and the Allied powers. The outcome of the war resulted in the fall of Germany, Russia, Austria-Hungary and Turkey. The Treaty of Versailles, known to be the final end to the war, was signed on June 28th, 1918.
8 million troops died.
21 million troops were wounded.
Over 200,000 men died in the trenches during the war.

More on World War I