Short answers, pulled from the story.
Operation Himmler was a series of false-flag attacks staged by Nazi Germany in August 1939 to create the appearance of Polish aggression against Germany. The goal was to manufacture a pretext for the German invasion of Poland, which began on the 1st of September 1939, and to potentially confuse Poland's allies, the United Kingdom and France, into delaying their declaration of war.
The operation was named after its originator, Heinrich Himmler. Reinhard Heydrich supervised it, and Heinrich Muller managed its day-to-day execution. The agents who carried out the staged attacks were members of the SS and the SD.
On the night of the 31st of August 1939, a group of German operatives dressed in Polish uniforms and led by Alfred Naujocks seized the German radio station Sender Gleiwitz in Gliwice and broadcast a short anti-German message in Polish. Prisoners, most likely from the Dachau concentration camp, were left dead at the scene alongside a local Polish-Silesian activist who had been arrested the day before.
Operation Konserve took its name from the German word for canned goods, Konserve. Planners used that code word to refer to the concentration camp prisoners who were killed by lethal injection, dressed in Polish uniforms, and left at the staged attack sites as false evidence of Polish aggression.
In his the 1st of September 1939 speech to the Reichstag, Hitler cited 21 border incidents as justification for Germany's "defensive" response to Poland. He claimed Polish regular soldiers had fired on German territory since 5:45 in the morning of that day, framing the invasion as retaliation rather than aggression.
Operation Himmler convinced very little international opinion about the German claims. The United Kingdom and France declared war on Germany regardless, which had been one of the key outcomes Hitler hoped to prevent. The operation failed at its most ambitious diplomatic objective.