Reinhard Heydrich (1904-1942) was a senior Nazi security official, one of the few assassinated by deliberate Allied planning because he was seen as among the most dangerous of the Nazis. Dismissed as a naval officer, he headed the Sicherheitsdienst (SD) security service of the Schutzstaffel (1931-1942), added the Gestapo (1934-1936), the SIPO security police of the Gestapo and KRIPO criminal police (1936-1932), and the overall Reichssicherheitshauptamt (RSHA} Reich Main Security Service RSHA. While still chief of the RSHA, Heydrich served as Acting Reich Protector of Bohemia and Moravia from 1941 until 1942,  he was assassinated
Without any question, he both had complex personality and motives, and also was one of the most intelligent and hard-working senior Nazis. A number of the leadership saw him as a potential successor to Hitler. Joachim Fest spoke of him as superficially similar to the French revolutionary, Saint-Just. He did
share with him an utter lack of feeling, no matter how much it cost him, and, like Saint-Just, he only considered it difficult for those who shrank from graves. But there were many differences between them. Heydrich was coarser and more frivolous. 
Biographies here often start in reverse chronological order, but Heydrich’s early life, and path to the Nazis, helps understand him.
Even to look at Heydrich set him apart from Nazi leaders such as Hitler, Goebbels and Himmler. While these often-unfit brown-haired, brown-eyed men preached their ”Aryan” ideal, Heydrich was tall, blond, blue-eyed and a champion athlete and pilot. Nevertheless, as a boy, he fought a whispering campaign that he had Jewish ancestry.
Born to a family of musicians, in Halle an der Saale, 20 miles northwest of Leipzig, “ To the end of his life, he remained a gifted musician with the ability to bring rivals to tears with his cello.” .
Neither his childhood nor young adulthood were untroubled. Bruno, his father, was first an opera singer, and then founded the Halle music conservatory in 1901. The conservatory struggled financially in the First World War and its aftermath.
While the only suggestion that he was Jewish came from the surname of his father's stepfather, "Suess", there is no indication that Suess was actually Jewish, and he may have acted out anti-Semitism and nationalism to disprove the rumor.  Heydrich, still in his teens, was seduced by racist (voelkisch) nationalism and watched demonstrations, strikes, and street battles in Halle during the last year of the war and the revolutionary chaos that followed. Despite these extra-curricular activities, he maintained excellent grades and earned his high school diploma in the spring of 1922.
His father wanted his son, with undoubted musical talent, to follow him, but he enlisted, as soon as he was eligible, as an officer candidate in the German Navy.
The German Navy excluded Jews and encouraged nationalism, which may have made him more secure. As a naval officer, Heydrich specialized in signals and communications. He developed strong technical skills, but did not mix well with his peers, and was disliked as a harsh disciplinarian by enlisted men.
He left the daughter of a senior naval officer to whom he had promised marriage for another woman, Lina von Osten, whom he would later marry. A military court of honor, scandalized by his disrespectful behavior during his hearing, found him to have dishonored the officer corps of the Reich Navy and compelled him to resign his commission in April 1931.
“He was an intensely competitive sportsman and airplane pilot, who much to the distress of his superiors, insisted on flying missions over France, Norway and southern Russia. Perhaps most important for his career, he was an energetic, imaginative workaholic who understood the implicit intentions of his superiors and how to transform those dreadful visions into policy. 
An unemployed civilian in the midst of the Depression with a fanatical National Socialist as his new bride, Heydrich was introduced to SS chief Heinrich Himmler by a family friend. Himmler had been struggling to create an internal intelligence service for the Party, and, with only a short conversation. Himmler was pleasantly surprised and immediately, in August 1931, commissioned him into the SS and charged him with developing the SD. This was a time at which the SS, as opposed to the SA, was bringing officers and intellectuals into its ranks. It would dominate the SA in a few years.
Heydrich quickly brought him the first coherent proposal. Seeking at that time to create an internal intelligence service for the Nazi party, Himmler was so impressed by Heydrich's proposals that he brought him into the SS in August 1931 and tasked him with developing the SD. By January 1933, the SD under Heydrich's leadership had become the most significant intelligence agency within the Nazi party. In June 1934, Nazi party Deputy Chief Rudolf Hess named it the sole agency authorized to gather political intelligence inside the Third Reich.
Himmler took command of the Nazi-controlled Bavarian police department on 1 April 1933, he made Heydrich his deputy.
When Himmler's SS became independent of the SA after the purge of SA chief of staff Ernst Röhm and the top SA leadership on June 30-July 2, 1934, Heydrich took command of the Gestapo while remaining chief of the SD.
Nine days after his appointment as Reichsführer SS and Chief of German Police on June 17, 1936, Himmler appointed Heydrich chief of the newly established Security Police (Nazi Germany) (SIPO) Main Office (Hauptamt Sicherheitspolizei) which combined the Gestapo and the KRIPO
These “visible” enemies, however, possessed international ties and aligned themselves with “camouflaged” enemies, who sought from within to destroy the “natural” bond between the Nazi leadership and the German people. As Heydrich explained in April 1936, racially conscious Germans must realize that “effective struggle against the enemy must derive from recognition of the fact that all visible, apparent enemies are but the tip of the iceberg of eternal, unchanging dangerous spiritual forces.” The enemies themselves were “eternally the same”: “the Jew, the Freemason, and the politically-oriented cleric.” The “invisible,” submerged, camouflaged ideological wellsprings of these “enemies” lay in the “infectious residue” of “Jewish, liberal and Freemasonic spirit,” modes of thinking (democracy, communism, Christian and liberal individualism) that were outgrowths of allegedly inherited racial characteristics. Only the complete destruction of the “biological sources” of such thinking would eliminate the danger presented by such influences.
From 1936 until 1939, Heydrich's formal title was “Chief of the Security Police and the SD.” After Poland was invaded, Himmler formally linked the Security Police and SD by decreeing the establishment of the RSHA on September 27, 1939, under Heydrich's command. So potentially powerful was the new agency that Heydrich kept its formal existence a secret until his death in 1942. Correspondence going outside the RSHA bore the pre-1939 letterhead: “the Chief of the Security Police and the SD.”.
Due to their shared naval background, he had a relationship of both friendship and competition with Rear Admiral Wilhelm Canaris, head of the military Abwehr counterintelligence service. Canaris is reputed to have had documents that pointed to Heydrich having Jewish ancestry. 
In 1938, leadership of “Jewish matters” (Judenangelegenheiten) in the SD was under Oberstuermfuhrer Adolf Eichmann. His team demonstrated imaginativeby establishing a one]]-stop station in Vienna (Zentralstelle für jüdische Auswanderung) to facilitate the forced emigration of Jews from Austria and to finance those operations by extorting funds from wealthier members of the community. Heydrich encouraged the Kristallnacht, which included the arrest of 30,000 Jews.
As a result, Hermann Goering, then deputy to Hitler, authorized Heydrich on January 24, 1939, to develop plans for a “solution to the Jewish Question” in the German Reich. He would improve this for several years, presenting interim and then the final solution at the Wannsee Conference.
As Nazi Germany began military expansion, Heydrich created Operations Groups (Einsatzgruppen), initially in 1938, long before security forces consolidated into the RSHA. The first groups into Austria and the Sudetenland performed security and control, but not genocidal, activities; they did arrest “enemies”. They went into Austria after the Anschluss in March 1938 and into the Sudetenland after its annexation in early October 1938.
Heydrich had important roles both in provoking the war with Poland, and then in detaining and killing Polish opposition.
Heydrich drected the ruse that Germany would use to attack Poland in “self-defense”: a fake raid on the Gleiwitz radio station, leaving dead concentration camp prisoners in Polish uniforms, code-named “canned goods”. The 31 August raid was led by SD Sturmbannfueher Alfred Naujocks, who had participated in the Venlo Incident.
Eitsatzgruppen in Poland
Einsatzgruppen, no longer new, followed the German conventional forces into Poland was invaded in September 1939. They began large-scale killings of Polish elites they considered threats to Germany, although perhaps the worst mass murder, at Katyn Forest, was carried out by the Soviets. There was forced relocation and incidental killing of Jews, but not yet systematic execution of groups.
Barbarossa and the Final Solution
- See also: Operation Barbarossa
That changed with Operation Barbarossa, the invasion of the Soviet Union on 22 June 1941. The Einsatzgruppe followed the armies, but with much more lethal intent, intensifying by the fall.
The Final Solution
While it has never been confirmed, since the participants are dead, Hitler appears to have given verbal orders, in the summer of 1941, to Goering, then Hitler’s deputy, and Himmler, head of the SS, to begin planning what Goering, told Heydrirch on 31 July: coordinate the resources of the Reich “for a total solution of the Jewish Question in the area of German influence in Europe.” To this end, Heydrich was to submit a draft measures proposed “to implement the desired final solution of the Jewish Question.”
Within the Reich Commissariat Ostland, comprising the Baltic states and much of Belarus, directed by Alfred Rosenberg, the Gestapo arranged for deportation of Jews there, as well as in Germany, to be taken to the SIPO/SD run Einsatzkommandos to be killed.
Communist resistance flourished in Bohemia and Moravia, generally considered part of Czechoslovakia, after the Soviet Union was invaded. Hitler, displeased with the lack of security provided by Reich Protector Konstantin von Neurath, naming Heydrich his temporary replacement. Heydrich kept the RSHA post.
On taking command, he announced a policy of dividing the population into three categories: 
- Racially unsound and ideologically unfit: Deportation to the East
- Racially unsound and ideologically fit: Sterilization
- Racially sound but ideologically questionable: Attempt to Germanize; shooting if that failed.
He began focused targeting on the real and perceived opposition. Heydrich first ordered a narrow wave of terror targeting real and perceived leaders of opposition in the Czech lands. In October and November 1941, Protectorate special courts sentenced 342 people to death and turned 1,289 “over to the Gestapo.”
Heydrich as acting Reich Protector then courted Czech industrial workers and farmers, whose productive capacity was necessary to the German war effort, with wages and benefits packages equivalent to those of their German counterparts. The result of his policies was a 73% reduction in acts of sabotage within six months.
By spring of 1942, the German authorities could boast of a pacification of the Protectorate. The Czech government-in-exile, alarmed with his success, established an assassination mission against him, Operation Anthropoid, both to destroy his effectiveness but also to draw reprisals onto their people, reducing support for Germany.
He may have assumed his pacification was effective, or simply drove around in an open vehicle, with minimal security, as part of his risk-taking behavior. Czech agents, parachuted into Prague, mortally wounded him with a grenade on 27 May. He leaped out of his car and shot at them, but later died of infection on 4 June.
- Reinhard Heydrich, U.S. Holocaust Memorial Museum
- Joachim C. Fest, The face of the Third Reich: portraits of the Nazi leadership, Da Capo Press, p. 109
- George C. Browder (2004), Foundations of the Nazi Police State: The Formation of Sipo and SD, University of Kansas Press, p. 25
- Callum MacDonald, The killing of Reinhard Heydrich: the SS "Butcher of Prague", DaCapo, pp. 10-11
- Fest, p. 105
- Roger Moorhouse (29 July 2008), "Alfred Naujocks", Historian at Large
- Richard J. Evans, The Third Reich at war, Penguin, p. 274
- Evans, p. 275