Adolf Hitler, chancellor of Germany, ruled as a dictator and spread Nazi ideology throughout the country, which established that Germans were racially superior while villanizing "inferior" people such as Jews, Slavs, the physically disabled, and opposers to Nazism.
Hitler was elected in 1933 and promised to make Germany strong again, following Germany's defeat in World War I. His main goals were to purify the German race and to spread east for more living space.
World War II began in September 1939 with the German invasion of Poland. The use of extermination camps and mass murders of Jews and other "inferior" people began in late 1941.