Oligarchy is a where a group of individuals, wealthy, royalty, or powerful military figures, run the Government. Families of Oligarchies raise and mentor their Children to become receivers of the power of Oligarchy. This kind of power can not be practiced openly, the oligarchs prefer to stay "The power behind the throne", applying control through economic means. Many people like to think of Oligarchy being similar to Communism.
Nazi party ruled Germany 1921-1945. Hitler became leader in 1921-1933. Since Hitler became chancellor of Germany, his Nazi government assumed dictatorial power.
After leaving prison, Hitler goal was to gain power during the election. In 1929 Germany entered a period of economic depression, and the Nazis blamed the ruling of Government and began to win elections.
The sale of Hitler's political autobiography Mein Kampf, which was called the bible of the Nazi, made Hitler a millionaire. By the the Nazi party took over, free copies of Mein Kampf were given to every newly wed couples.
Hitler also gave speeches blaming Jews and Marxist for the problem Germany had after WW1 and spreading German nationalism and anti-semitism. Hitler's speeches rose high in the ranks of the Nazi power.