Germany, Austria-Hungary's ally, also declares war upon Serbia. Russia declares war on Germany, too. Because Germany declared war on Serbia and not upon Russia, France, a Russian ally, had no reason to declare war upon Germany. Therefore, France takes a neutral stance in the war, meaning the British Empire also does not join the war.
Because of France's position, Germany only has one front to fight, allowing them to focus all of their attention on Russia. Germany and Austria-Hungary capture Moscow, forcing Russia to surrender in 1919. Due to family ties, Russia only has to cede large amounts of territory and make needed reforms such as abolishing serfdom.
Because of Germany and Austria Hungary's victory, the age of absolute monarchies lives on. World War II never occurs and the October Revolution never happens.
This is a limited timeline, meaning that it only goes to 1935...
Timeline of Events
1917- The Ottoman Revolution starts. Russian forces sweep around through Anatolia and counter-attack Bulgaria. The Ottoman Empire crumbles.
1919- The Treaty of Salzburg ends the Eastern War. The new nations of Poland, Ukraine, Livonia, Finland, Turkey, Mesopotomia, Assyria, Palestine, Arabia, and Armenia are created.
1925- Britain invades Arabia.
1930- Trenches are first used. Britain begins a blockade of Germany. Russia is made into a full democracy; the Czar has no more political power.
1931- Belgium is occupied by Germany.
1932- Austria-Hungary joins Germany's side of the War.
1934- The Treaty of Fez ends World War I, in a status quo ante bellum.