Reinhard Heydrich, German SS officer and a principle architect of the Holocaust (born 1904)

Reinhard Tristan Eugen Heydrich was a high-ranking German SS and police official during the Nazi era and a principal architect of the Holocaust. He held the rank of SS-Obergruppenführer und General der Polizei. Many historians regard Heydrich as one of the darkest figures within the Nazi regime. Adolf Hitler described him as "the man with the iron heart."

The Schutzstaffel was a major paramilitary organisation under Adolf Hitler and the Nazi Party in Nazi Germany, and later throughout German-occupied Europe during World War II.

The Holocaust, known in Hebrew as the Shoah, was the genocide of European Jews during World War II. From 1941 to 1945, Nazi Germany and its collaborators systematically murdered some six million Jews across German-occupied Europe, around two-thirds of Europe's Jewish population. The murders were committed primarily through mass shootings across Eastern Europe and poison gas chambers in extermination camps, chiefly Auschwitz-Birkenau, Treblinka, Belzec, Sobibor, and Chełmno in occupied Poland. Separate Nazi persecutions killed millions of other non-Jewish civilians and prisoners of war (POWs); the term Holocaust is sometimes used to include the murder and persecution of non-Jewish groups.

June 4 is the 155th day of the year in the Gregorian calendar; 210 days remain until the end of the year.