'Adler' (i) was a German unsuccessful operation to destroy aircraft in neutral Switzerland (16 June 1940).

Otherwise known as 'Warthegau', this sabotage mission appears to have been triggered by the anger of Generalfeldmarschall Hermann Göring, commander-in-chief of the Luftwaffe, that German aircraft straying into Swiss airspace on 2 and 8 June had been attacked by Swiss fighters which, adding insult to injury in Göring’s mind, were Messerschmitt Bf 109 aircraft supplied by Germany.

Planned and undertaken by the Abwehr, the operation involved a party of 10 saboteurs, two of them Swiss nationals and the other eight men of Hauptmann Dr Theodor von Hippel’s Bau-Lehr-Bataillon zbv 800 special forces unit. Three of the saboteurs entered Switzerland at Martinsbruck and the other seven reached Kreuzlingen during the night of 12/13 June. The whole undertaking had been rushed in its preparation and also very badly planned, for all of the men were identically but inappropriately dressed in knickerbockers, berets and capes, and carrying paratrooper knapsacks. The men were all arrested.