Heinrich Luitpold Himmler was a German Nazi politician and military leader. He was the 4th Reichsführer of the Schutzstaffel (Protection Squadron; SS) from 1929 to 1945. He was a leading member of the Nazi Party, and one of the most powerful figures in Nazi Germany. He was also one of the main architects of the Holocaust, the genocide of the Jewish population of Europe.
After serving in a reserve battalion during World War I without seeing combat, Himmler went on to join the Nazi Party in 1923. In 1925, he joined the SS, which was initially a small paramilitary arm of the Nazi Party that served as a bodyguard unit for Adolf Hitler. Himmler rose steadily through the SS's ranks to become Reichsführer-SS by 1929. Under Himmler's leadership, the SS grew from a 290-man battalion into one of the most powerful institutions in Nazi Germany. Over the course of his career, Himmler acquired a reputation for good organisational skills and for selecting highly competent subordinates, such as Reinhard Heydrich.