Original: Built upon the Nazi ideology , the SS , under Heinrich Himmler 's command , was responsible for many of the crimes against humanity perpetrated by the Nazis during World War II , and most of the particularly egregious ones .
Simplified: The Nazis saw the SS as an elite unit , the partys '' Praetorian Guard , '' with all SS personnel selected on the principles of racial purity and unconditional loyalty to the Nazi party .