Complex sentence: On 8 August 1940 Köstring was warned by General Franz Halder that "he would have to answer a lot of questions soon", making him one of a few people who knew what would happen with Russia despite the non-aggression pact.
Split into simpler sentences: On 8 August 1940 Köstring was warned by General Halder that "he would have to answer a lot of questions soon". Making him one of a few people who knew what would happen with Russia despite the Non-aggression pact.