Many historians regard Heydrich as the darkest figure within the Nazi regime; Adolf Hitler described him as "the man with the iron heart". He was the founding head of the Sicherheitsdienst (Security Service, SD), an intelligence organisation charged with seeking out and neutralising resistance to the Nazi Party via arrests, deportations, and murders. He helped organise Kristallnacht, a series of coordinated attacks against Jews throughout Nazi Germany and parts of Austria on 9–10 November 1938. The attacks were carried out by SA stormtroopers and civilians and presaged the Holocaust. Upon his arrival in Prague, Heydrich sought to eliminate opposition to the Nazi occupation by suppressing Czech culture and deporting and executing members of the Czech resistance. He was directly responsible for the Einsatzgruppen, the special task forces that travelled in the wake of the German armies and murdered more than two million people by mass shooting and gassing, including 1. 3 million Jews.