Germany could not pay WWI damage debt and the economy suffered. They needed a leader to help them. Other countries suffered damages also and needed leaders. Many new leaders rose to power promising to fix these problems. These new leaders caused their own set of problems, starting a war.
In the 1920s Adolf Hitler rose to power. He started a political party named the Nazis. In 1933 the Nazis took over Germany. He ruled with complete power, and used force to control people. Through the late 1930s millions of innocent people were put in concentration camps just because they didn't aggree.
In 1919 he created a fascist party and made himself the dictator. By 1922 Italy was in a chaotic state and Mussolini said that only he could help Italy restore order. He was given authority over Italy and slowly decreased the chaos. He later sighted the pact of steel making a military alliance with Germany.
He was a career solider who got higher in ranks until the 1930s. The economic structure was weak he joined a right leaning rebel movement. He then lead an uprising taking control of Spain after the Spanish civil war. He later controlled a brutal military dictatorship where thousands of people were killed or thrown in jail during his early reign.