Reichstag Fire

Firemen work on the burning Reichstag

February 27, 1933:

 Reichstag fire: Germany's parliament building in Berlin, the Reichstag, is set on fire. The Reichstag fire (German: Der  Reichstagsbrand (help·info)) was an arson attack on the Reichstag building in Berlin on 27 February 1933. The event is seen as pivotal in the establishment of Nazi Germany.
At 21:25 (UTC +1), a Berlin fire station received an alarm call that the Reichstag building, the assembly location of the German Parliament, was ablaze. The fire started in the Session Chamber, and, by the time the police and firefighters had arrived, the main Chamber of Deputies was engulfed in flames.
Inside the building, a thorough search conducted by the police resulted in the finding of Marinus van der Lubbe. Van der Lubbe, council communist and unemployed bricklayer, had recently arrived in Germany, ostensibly to carry out his political activities. The fire was used as evidence by the Nazis that the Communists were beginning a plot against the German government. Van der Lubbe and four Communist leaders were subsequently arrested. Adolf Hitler, who had been sworn in as Chancellor of Germany four weeks before, on 30 January, urged President Paul von Hindenburg to pass an emergency decree to counter the "ruthless confrontation of the Communist Party of Germany".^[2] With civil liberties suspended, the government instituted mass arrests of Communists, including all of the Communist parliamentary delegates. With them gone and their seats empty, the Nazis went from being a plurality party to the majority; subsequent elections confirmed this position and thus allowed Hitler to consolidate his power.
Meanwhile, investigation of the Reichstag fire continued, with the Nazis eager to uncover Comintern complicity. In early March 1933, three men were arrested who were to play pivotal roles during the Leipzig Trial, known also as the "Reichstag Fire Trial": Bulgarians Georgi Dimitrov, Vasil Tanev and Blagoi Popov. The Bulgarians were known to the Prussian police as senior Comintern operatives, but the police had no idea how senior they were; Dimitrov was head of all Comintern operations in Western Europe.
Historians disagree as to whether Van der Lubbe acted alone or whether the arson was planned and ordered by the Nazis, then dominant in the government themselves, as a false flag operation. The responsibility for the Reichstag fire remains an ongoing topic of debate and research.

I think we ought to weigh whether any large political provocation might be a false flag operation.  They are not common, but the potential damages of such an operation are tremendous.