Complex sentence: The pre-war Chief of the General Staff was Colonel General Helmuth von Moltke (The Younger) and the "Oberste Heeresleitung" was the command staff led by Moltke as Chief of the General Staff of the Army.
Split into simpler sentences: The pre-war Chief of the General Staff was Colonel General Helmuth von Moltke. The "Oberste Heeresleitung" was the staff led by Moltke as Chief of the General Staff of the Army.