Reichstag fire
Six days before the scheduled election date, the German parliament building was set alight in the Reichstag fire, allegedly by the Dutch Communist Marinus van der Lubbe. That event reduced the popularity of the KPD and enabled Hitler to persuade Hindenburg to pass the Reichstag Fire Decree as an emergency decree according to Article 48 of the Weimar Constitution. The emergency law removed many civil liberties and allowed the arrest of Ernst Thälmann and 4,000 other leaders and members of the KPD shortly before the election, suppressing the Communist vote and consolidating the position of the Nazis.