Altona Bloody Sunday (German: Altonaer Blutsonntag) is the name given to the events of July 17, 1932 when a recruitment march by the Nazi SA led to violent clashes between the police, the SA and supporters of the Communist Party of Germany (KPD) in Altona, which at the time belonged to the Prussian province of Schleswig-Holstein but is now part of Hamburg. Eighteen people were killed. The national government under Reich Chancellor Franz von Papen and Reich President Paul von Hindenburg used the incident as a rationale to depose the acting government of the Free State of Prussia by means of an emergency decree in what came to be known as the Prussian coup d'état of July 20, 1932.