Rare and precious stamp showing Austrian Chancellor Engelbert Dollfuss, who was assasinated by Nazis in an coup attempt in 1934. He introduced alternative version of fascism in Austria (Austrofascism) styled after Italian regime of Mussolini. He also delegalized Nazi party, which was likely the reason for his eventual assasination by Nazi agents. 
After Anschluss of Austria by Germany in 1938, the remaining stamps showing Dollfuss were confiscated and destroyed. That's what made them now scarce and precious collectible.