After the attack on Reinhard Heydrich, the Nazi leadership immediately responded with broad retaliatory measures against the Czech civilian population. As this May 27, 1942, telex from Himmler to State Secretary Karl Hermann Frank makes clear, these measures included the mass arrest and shooting of alleged “oppositional intellectuals.” Here, Himmler instructs Frank to imprison 10,000 members of the oppositional Czech intelligentsia and to shoot the 100 most important perpetrators that very same night. He ends by noting that he will call Frank later that night. The search for the true attackers, who were hiding in the crypt of Prague’s Charles Borremeo Church, yielded nothing at first. After their hiding place was betrayed, they committed suicide on June 18, 1942.