The OKW ran military operations on the Western front while its rival organization the Oberkommando des Heeres (OKH, Army High Command) controlled operations on the Eastern front. In the west operations were further split between the OKW and the Oberbefehlshaber West (OBW, Commander in Chief West), who was Generalfeldmarschall Gerd von Rundstedt. There was even more fragmentation as naval and air operations had their own commands (Oberkommando der Marine (OKM) and Oberkommando der Luftwaffe (OKL)) which, while theoretically subordinate, were largely independent from OKW or the OBW.
The OKW had been formed in 1938 following the Blomberg Affair which led to the dismissal of Werner von Blomberg and the dissolution of the Reichswehrministerium (Reichs Ministry of War). The OKW was headed for the entire war by Wilhelm Keitel and reported directly to Hitler, from whom most operational orders actually originated as he had made himself Oberster Befehlshaber der Wehrmacht (Supreme Commander of the Armed Forces) and Oberbefehlshaber des Heeres (head of the OKH). Alfred Jodl was Keitel's Chef des Wehrmachtführungsstabes (Chief of Operation Staff), while Walter Warlimont was Deputy Chief.