Oberkommando des Heeres in the context of "Oberkommando der Wehrmacht"

The Manstein plan or Case Yellow (German: Fall Gelb; also known after the war as Unternehmen Sichelschnitt a transliteration of the English Operation Sickle Cut), was the war plan of the German armed forces (Wehrmacht) for the Battle of France in 1940. The original invasion plan was an awkward compromise devised by General Franz Halder, the chief of staff of Oberkommando des Heeres (OKH, Army High Command) that satisfied no one. Documents with details of the plan fell into Belgian hands during the Mechelen incident on 10 January 1940 and the plan was revised several times, each giving more emphasis to an attack by Army Group A through the Ardennes, which progressively reduced the offensive by Army Group B through the Low Countries to a diversion.

In the final version of the plan, the main effort of the German invasion was made against the Ardennes, the weakest part of the Allied line, where the defence was left to second-rate French divisions in the Second Army and the Ninth Army, on the assumption that the difficulty of moving masses of men and equipment would give the French plenty of time to send reinforcements if the area was attacked. The Seventh Army, which had been the most powerful part of the French strategic reserve, had been committed to a rush through Belgium to join with the Dutch Army to the north, in the Breda variant of Plan D, the Allied deployment plan.

Franz Halder (30 June 1884 – 2 April 1972) was a German general and the chief of staff of the Army High Command (OKH) in Nazi Germany from 1938 until September 1942. During World War II, he directed the planning and implementation of Operation Barbarossa, the 1941 invasion of the Soviet Union. Halder became instrumental in the radicalisation of warfare on the Eastern Front. He had his staff draft both the Commissar Order (issued on 6 June 1941) and the Barbarossa decree (signed on 13 May 1941) that allowed German soldiers to execute Soviet citizens for any reason without fear of later prosecution, leading to numerous war crimes and atrocities during the campaign. After the war, he had a decisive role in the development of the myth of the clean Wehrmacht.

Halder began his military service in 1914. In 1937 he met and became a supporter of Adolf Hitler. Halder participated in the strategic planning for the 1939 German invasion of Poland. The plans authorised the SS to carry out security tasks – on behalf of the army – that included the imprisonment or execution of Poles. In July 1940 he began planning for the Axis invasion of the Soviet Union, Operation Barbarossa, which began on 22 June 1941. That summer Halder engaged in a long-running and divisive dispute with Hitler over strategy. Hitler removed Halder from command in September 1942. After the 20 July 1944 plot to assassinate Hitler, Halder was arrested as it came to light that he had been involved in an earlier plot, leading to his imprisonment. As chief of OKH General Staff, he had kept extensive notes, later published as The Halder Diaries.

The Bendlerblock (German pronunciation: [ˈbɛndlɐˌblɔk] ) is a building complex in the Tiergarten district of Berlin, Germany, located on Stauffenbergstraße (formerly named Bendlerstraße). Erected in 1914 as headquarters of several Imperial German Navy (Kaiserliche Marine) offices, it served the Ministry of the Reichswehr after World War I. Significantly enlarged under Nazi rule, it was used by several departments of the Oberkommando der Wehrmacht (OKW) from 1938, especially the Oberkommando des Heeres and the Abwehr intelligence agency.

The building is notable as the headquarters of a resistance band of Wehrmacht officers who staged the 20 July plot against Adolf Hitler in 1944. As the leaders of the conspiracy were summarily shot in the courtyard, the Bendlerblock also includes the Memorial to the German Resistance. Since 1993, the building complex has served as a secondary seat of the German Federal Ministry of Defence.

Reinhard Gehlen (3 April 1902 – 8 June 1979) was a German military and intelligence officer, later dubbed "Hitler's Super Spy," who served the Weimar Republic, Nazi Germany, and West Germany, and also worked for the United States during the early years of the Cold War. He led the Gehlen Organization, which worked with the CIA from its founding, employing former SS and Wehrmacht officers, and later became the first head of West Germany's Federal Intelligence Service (BND). In years prior, he was in charge of German military intelligence on the Eastern Front during World War II and later became one of the founders of the West German armed forces, the Bundeswehr.

The son of an army officer and World War I veteran, in 1920 Gehlen joined the Reichswehr, the truncated army of the Weimar Republic, and was an operations staff officer in an infantry division during the invasion of Poland in 1939. After that he was appointed to the staff of General Franz Halder, the Chief of the Army High Command (OKH), and quickly became one of his main assistants. Gehlen had a significant role in planning the German operations in Greece, Yugoslavia, and the Soviet Union. When the Red Army continued to fight after the initial German success during Operation Barbarossa, in the spring of 1942 Gehlen was appointed by Halder as director of Foreign Armies East (FHO), the military intelligence service of the OKH tasked with analyzing the Soviet armed forces. He achieved the rank of major general before he was dismissed by Adolf Hitler in April 1945 because of the FHO's alleged "defeatism" and accurate but pessimistic intelligence reports about Red Army military superiority.