The German original of the secret protocols was presumably destroyed in the bombing of Germany, but in late 1943, Ribbentrop had ordered that the most secret records of the German Foreign Office from 1933 on, amounting to some 9,800 pages, be microfilmed. When the various departments of the Foreign Office in Berlin were evacuated to Thuringia at the end of the war, Karl von Loesch, a civil servant who had worked for the chief interpreter Paul Otto Schmidt, was entrusted with these microfilm copies. He eventually received orders to destroy the secret documents but decided to bury the metal container with the microfilms as a personal insurance for his future well-being. In May 1945, von Loesch approached the British Lt. Col. Robert C. Thomson with the request to transmit a personal letter to Duncan Sandys, Churchill's son-in-law. In the letter, von Loesch revealed that he had knowledge of the documents' whereabouts but expected preferential treatment in return. Colonel Thomson and his American counterpart Ralph Collins agreed to transfer von Loesch to Marburg in the American zone if he would produce the microfilms. The microfilms contained a copy of the Non-Aggression Treaty as well as the Secret Protocol. Both documents were discovered as part of the microfilmed records in August 1945 by the State Department employee Wendell B. Blancke, head of a special unit called "Exploitation German Archives" (EGA).
Why did Karl von Loesch destroy the microfilm?