In 1923 Hitler was a well-known and charismatic political speaker in Germany, but he was not yet the powerful leader that popular history remembers. He attempted to organize an overthrow of the German government by the Nazi Party, but he misjudged the moment and the revloution was a spectacular failure. Hitler was tried and imprisoned, but the momentum for his cause continued to build as many millions of Germans began to sympathize with Hitler. He spent his time in prison writing Mien Kempf which clearly outlines his horrifying philosophy. 

The nonagression pact signed between Germany and the Soviet Union in 1939 involved both powers pledging not to attack each other. It also featured a plan to divide the nation of Poland between the two powers during the Second World War.

World War Two is often referred to as "the Great Patriotic War" in Russian society. This is probably derived from the immense civilian and military losses that Russia suffered in the conflict and the terrible sacrifices made by so many individuals for the cause of Russian survival.

From 1939 to 1940, relations between Nazi Germany and the Soviet Union were distrusting but in theory amicable. The two nations had signed a treaty promising not to attack one another and to work together to divide Poland between them. As their borders grew closer and closer, it became clear that neither Hitler nor Stalin was willing to maintain peace. Nazi Germany launched Operation Barbarossa in 1941 to try and swiftly take down the Soviet state; however, it became a war of attrition and ended with the destruction of the German army and the devastating Soviet march to Berlin.

The Siege of Stalingrad took place for six months from August of 1942 to February of 1943. It involved the forces of Nazi Germany laying siege to the Soviet city of Stalingrad. The Nazi forces inflicted heavy civilian casualties on the Soviet population, but were unable to hold the city for any length of time. The siege ended with the complete destruction of the Nazi Sixth Army and the forced retreat of Nazi forces out of Soviet territory.

The Great Purge is the name given to a campaign of political repression and widespread persecution undertaken by the government of Josef Stalin between 1936 and 1940. It involved the imprisonment or execution of Red Army leaders thought to be disloyal to Stalin, hundreds of thousands of members of the peasantry, members of the Communist Party leadership, and even some members of Stalin's inner circle. It had several consequences, not least of all the weakening of the Red Army, due to the massive loss of military experience caused by the execution of so many experienced military leaders.

The Molotov-Ribbentrop Pact was a treaty of non-aggression signed between Nazi Germany and the Soviet Union in the month before World War Two began with Nazi invasion of Poland. As well as promising that the two nations would not attack each other during the coming conflict, it also secretly divided most of the nations of Eastern Europe into areas of Soviet and Nazi influence.

The Domino Theory became an important part of American foreign policy during the Cold War. It states that once one country falls under the influence of communism, there is a heightened chance that its neighboring countries will also succumb. It was the main motivation behind several of the United States' conflicts in the twentieth century such as the Korean War and the Vietnam War.

Karl Marx, writer of The Communist Manifesto, expected the communist revolution to take place first in Britain, Germany, or the United States. That it should happen first in Russia, a comparably undeveloped country, would have been a massive surprise to Marx. 

In the aftermath of World War II, the allied powers and several other democratic nations formed NATO, an agreement to provide for the cooperative growth of capitalist societies and to counter the rising threat of Soviet influence. The Warsaw Pact was formed shortly after as a countermeasure. It incorporated all the communist nations of Eastern Europe into a treaty with the Soviet Union.