Although signed into an alliance with France and Russia, Britain originally wanted to remain primarily neutral in the First World War. Certainly, Britain did not want to fully commit its forces to the conflict. However, Britain was sworn to defend Belgian sovereignty. Once Germany invaded Belgium, Britain was forced into the war on the side of France and Russia against the Germans. 

David Lloyd George was the Prime Minister of England from 1916-1922. Georges Clemenceau was Prime Minister of France from 1917 to 1920. Both men were influential in reordering Europe after World War One at the Paris Peace Conference. 

World War One began on the Western Front with a massive German troop movement through Belgium and into North-Eastern France. In response to German troops moving through Belgium and occupying the nation, Britain declared war (it had promised to protect Belgian neutrality and was allied with the French). The French and the British stalled the German offensive at the Battle of the Marne, and the mobile period of the First World War ended, to be was replaced with years of brutal trench warfare. 

The German U-boat policy of unrestricted submarine warfare was an important strategy in the Atlantic theatre of the First World War. In an attempt to cut off the British isles from foreign trade, the German submarines would sink any merchant boat headed there. This caused the sinking of American ships and helped turn public opinion in America towards war against Germany.

The leader of Germany during the First World War was Kaiser Wilhelm II. He replaced Bismarck as ruler of Germany in 1890 and set the nation on a course for warfare from the very beginning. He was forced to abdicate power following the end of the war and German capitulation.

The Zimmerman Telegram was sent to Mexico by the German government during World War One. It was designed to preempt American involvement in the war in Europe by ensuring that Mexico would keep America distracted at home. The telegram was made public knowledge and was an important motivating factor in America's final decision to enter the conflict.

For much of the nineteenth century, the Russians had shown a distinct interest in the Balkan region. Russia wanted a port city to directly access the Mediterranean, but the Russians also saw themselves as the same, or similar, nationality as the Serbian people living in the Balkan region. The Serbs at the time were under the dominion of the Austria-Hungary Empire, and Russia sought to help free the Serbs.

The Russian legislature was called the Duma. It was created by the Tsar to give in to calls for democracy, but in reality, it had limited powers to effect legislation.

Rasputin was a religious mystic who held great influence over the Russian royal family. Much of his influence was derived from his ability to keep one of the royal children alive. (The boy was a hemophiliac.) When Nicholas II was away leading troops at the front, his wife ruled the government, and the fact that she was considered under the control of a mystic led to much public outcry. 

The Russian Revolution occurred in 1917 and saw Russia pulled out of the First World War. The monarchy was replaced by a communist government run by Lenin and the Bolsheviks. The Bolsheviks differed from the Mensheviks in that they favored an immediate and artificial revolution.