Complex sentence: Enraged at Himmler's duplicity, Hitler ordered von Greim and Reitsch to fly to Dönitz's headquarters at Ploen and arrest the "traitor" Himmler.
Split into simpler sentences: Enraged at Himmler's duplicity, Hitler ordered von Greim and Reitsch to fly to Dönitz's headquarters at Ploen. Von Greim was ordered to arrest the "traitor" Himmler.