From 10 July 1944 to 31 December 1944, von Thadden was Chief of Staff of Defence District Command I in Königsberg. In his capacity as the commander of the Königsberg defence district, he was at Adolf Hitler's headquarters on 20 July 1944, when the assassination attempt on Hitler took place. Shortly before, he had had a conversation with Stauffenberg and Chief of Staff Walther Buhle.