World War 1 set the stage for much of what made up World War 2 and featured the arrival of military air power, the machine gun and the combat tank.
The industrialized world went to war in 1914 after tensions spilt over from the assassination of then little-known Archduke Ferdinand. Allegiances forced parties to declare war on one another and, within time, the world was embroiled in what would come to be known as "The Great War" or the "War to End All Wars" (later to become chronologically recognized as "World War 1"). As powers geared up for the battlefield, the once-euphoric public were shocked that the "gentlemen's wars" of old had given way to dastardly implements such as chemical warfare, machine guns, fighter aircraft and armored vehicles of trench warfare - war was a bloody an affair as ever before. The conflict was primarily centered in Europe and fought between the Central Powers and the Triple Entente. The Central Powers were made up of the Austro-Hungarian Empire, the German Empire, the Ottoman Empire (modern-day Turkey) and the Kingdom of Bulgaria. The Triple Entente was forged of an alliance between Great Britain, France and Russia and later on went to include allies such as the United States and Italy by war's end.
By the conclusion of the years-long conflict (many suggested at the outset that this would be a short-lived war to be over by Christmas of 1914), millions lay dead or maimed for life and the empires of Germany, Austria-Hungary and Turkey were no more. The Russian Empire itself ceased to exist amidst internal political issues, bowing out of the war in 1917 to become the Soviet Union in 1922. The Allied victory was eventually ensured by the contributions and sacrifices of many. With the Austro-Hungarian and Ottoman Empires dissolved, Germany was handed much of the blame for the war - laying down the foundation of what would become World War 2.