In 1908 after training in cadet school von Hanneken joined the army as a Fähnrich. A year later he was promoted to Leutnant. In April 1917 he was transferred to the General Staff, and the year after he was promoted to Hauptmann.
In 1915 von Hanneken became Oberleutnant and aide to a regiment in World War I. In July 1916 von Hanneken was transferred to the 260th Reserve-Infantry-Regiment, where he served as leader of the Machine Gun-Company.
Interbellum
After the war von Hanneken was in 1919 among the officers who joined the German Reichswehr. Then he took a job in Reichswehr Ministry where he was the next year. Then from 1924 to 1927 he was transferred to Reichwaffenamt. From 1927 he led troops as a company commander, and it continued until in 1930 when he was promoted to Major. Three years later he was again promoted to Oberstleutnant. From 1935 he had command of a regiment and was thus promoted to Oberst. A year later, in 1936, he was transferred to Heereswaffenamt, where he became Chief of Staff. On 3 July 1937, he became responsible for the purchase of iron and steel. On 1 September 1939 he was appointed Head of Section II in the ministry of commercial. In 1940 he received the position as vice Secretary of State. That same year he was promoted to Generalleutnant and in 1941 he was General der Infanterie.
After the outbreak of World War II a supply crisis in the iron and steel division caused him problems, and only could save him. Delivery time had increased dramatically because over a period of two years von Hanneken had approved supplies that exceeded the amount of iron and steel that could be delivered. Hans Kehrl said nothing about this in its public records, but his caseworker did in return. Kehrl wrote in his memoirs that von Hanneken was not sufficiently decisive and was afraid of conflict. von Hanneken was also responsible for addressing the issues of coal to the steel industry. So on 6 June 1941 he raised at the 11th meeting in the problem that the demand for coal in the last four years had risen faster than supply. The European countries which were dependent on German coal only got 60% of the claimed amounts. From April 1941 domestic coal consumers had to accept a reduction of supplies of around 10%. This led to many closures of companies or reduction of operations. Domestic energy suppliers had to accept a reduction in coal consumption of 20%. In March / April 1942 von Hanneken was denied responsibility for the distribution of iron and steel, which were transferred to the so-called central planning. As a result of further changes in the tasks of Section II largely transferred to other bodies so Hanneken went on holiday in August 1942 and left Section II in October. On 12 October 1942 he took over the duties of Erich Lüdke as commander of the German forces in Denmark. He was responsible for defending the invasion and took a tougher line against the Danish resistance movement, which brought him into conflict with Werner Best. On 29 August 1943 von Hanneken imposed martial law in Denmark. It was the result of growing unrest, strikes and sabotage in the months before. Simultaneously, the Danish army and navy were dissolved and their personnel interned. von Hanneke was made aware of but was not otherwise involved in the action against the Danish Jews in early October 1943 led by Günther Pancke. On 19 September 1944 he backtracked over the dissolution of the Danish police. In January 1945 he was released from his command and replaced by Georg Lindemann. He was accused of corruption and by the German National-martial sentenced 8 years imprisonment. He was, however, pardoned by Adolf Hitler, who thought that they could not afford the luxury of letting von Hanneken sit in jail. Instead, von Hanneken was demoted to Major and sent to the front. At the end of the war he became an American prisoner. From there, he was extradited to Denmark, where in 1948 he was sentenced to 8 years imprisonment. At the Court he was acquitted on 9 May 1949. He was expelled from Denmark and lived thereafter retracted until his death in 1981.
