Operation Himmler
One of the darker details surrounding the beginning of World War II is how the Nazi regime manufactured incidents that could be presented as Polish aggression. In 1939, Operation Himmler, also known as Operation Konserve or "Canned Goods," was organized to create the appearance that Poland had attacked Germany.
The operation involved staged incidents on German territory, with German operatives posing as Polish attackers and manufacturing evidence of hostile Polish activity. In some cases, prisoners from concentration camps and other civilians were forced into the role of supposed Polish aggressors, making the fabricated attacks appear more convincing.
The incidents were then used by Nazi authorities as part of the justification for invading Poland. What makes Operation Himmler particularly significant is that the pretext for military action wasn't simply discovered or exaggerated after the fact, it was deliberately manufactured beforehand and presented as evidence of an attack that had never actually happened.