In 1939, Nazi forces staged an attack on a German radio station.
They shot a well-known Polish sympathizer and planted his body at the scene, reporting the attack as the work of Polish saboteurs.
The attack was part of a Nazi propaganda campaign called Operation Himmler, which involved a series of staged incidents intended to create the appearance of Polish aggression against Germany and provide a basis for the invasion of Poland.
http://encyclopedia.thefreedictionary.com/Gleiwitz+incident