Karl Ernst was from 1933 the commander (in German: "Gruppenführer", group leader) of the SA in Berlin and senior member of Nazi organization. He has been accused of being part of SA detachment that set fire to the Reichstag on 27 February 1933. During the 1934 purge known as The Night of the Long Knives, he was shot, together with some 150 SA leaders, by the SS firing squads at the Cadet School at Lichterfelde in Berlin. In one violent bloodletting, Hitler thus removed political rivals and potential sources of scandal, since Ernst and many other SA leaders had well-known homosexual connections.
Before joining Nazis, Ernst had been a bell-boy in a hotel and a bouncer at a gay nightclub. Ernst had first met Paul Rohrbein, Berlin's first SA commander, at the El Dorado, a favorite meeting place of Berlin's homosexual community. Soon after, due to their intimate mutual friendship, Ernst was nicknamed "Frau Rohrbein". In 1931, Rohrbein had introduced Ernst to an old comrade Röhm, the commander in chief of the whole SA, that had a reputation of being a homosexual fraternity. By April 1931, Ernst was promoted to a command within the SA and, by 1932, was elected to the Reichstag as a Nazi deputy.
- Martyn Whittock (2011). "5 THE REVOLUTION EATS ITS OWN CHILDREN: THE DESTRUCTION OF THE SA", A Brief History of The Third Reich: The Rise and Fall of the Nazis. Hachette. ISBN 978-18490-18166.