Next to Adolf Hitler, Heinrich Himmler was one of the most notorious and sinister figures who contributed to the rise and fall of the Third Reich, and, more significantly, to the horrors of the Holocaust.
In 1929, Hitler recruited Himmler to lead the Nazi S.S. (Schutzstaffel): a band of armed, uniformed men that started out as Hitler's bodyguards. Under Himmler's leadership, that band of thugs became something very different. When Himmler first took over the S.S. it only had about 200 men. After a year under Himmler, there were 3,000 S.S. By the time he finished with it, the S.S. dominated Germany and "was a name that struck terror throughout occupied Europe" (2.5.16).
Shirer characterizes Himmler as "a mild-mannered fellow whom people mistook […] for a small-town school master" (2.5.16). Even Shirer himself made that mistake when he first met him. But like Hans Frank's apparent cultivation and reasonableness, Himmler's mild-mannered veneer concealed the inhumanity underneath.
As the chief of the S.S., Himmler organized and oversaw the systematic execution of millions of people—the vast majority of them Jews. Under his command, the S.S. troops were responsible not only for the direct massacres of hundreds of thousands of people, but also for the systematic internment of the millions more who were murdered in the Nazi extermination camps.
In the final days of the Second World War, Himmler dropped out of Hitler's good graces when news broke that he had attempted to negotiate a secret peace with the Allies (6.31.113). Drawing from a witness testimony of the scene, Shirer tells us that the reaction in Hitler's underground bunker in Berlin was violent: "Men and women alike screamed with rage, fear and desperation, all mixed into one emotional spas" (6.31.114).
They didn't take it well.
Hitler banished Himmler from the party and ordered his arrest, but Himmler managed not to be caught by his fellow Nazis. Instead, he was apprehended by a band of British soldiers on May 21, 1945, and two days later he killed himself by poison, the signature suicide technique of the Nazis.