The son of a Prussian General, Guderian was commissioned into the Tenth Hanoverian Jaegar in 1908 but spent World War I as a signal and then a staff officer. After the war he specialized in military mechanical transport and helped develop Germany’s first tanks at a time when they were forbidden under the Versailles Treaty. On its abrogation, he was made Commander of one of the first three Panzer divisions and in 1938 published a highly influential book on the future of armored warfare, Achtung! Panzer! The book expanded his logic ideas on how German armored units should be built up. He had by then been promoted General der Panzertruppen and on the outbreak of the war was given command of the Nineteenth Corps, which he led in the Polish Campaign. For the Battle of France he was given a Panzer Group, his brilliant handling of which was a perfect demonstration of the concept of blitzkrieg – rapid armored breakthrough, supported by airpower, on a narrow front – which he propagated in his writings. It was his tanks which were the first to cross the Meuse, at Sedan (14 May 1940), and first to reach the Channel coast. In Russia in 1941 his Panzer Group, renamed Fourth Panzer Army, led the drive on Moscow, but Hitler’s midsummer decision to switch the main effort towards Kiev and Leningrad involved Guderian in an insubordinate dispute with the Fuhrer. The rightness of his judgment did not save him and he was dismissed on 25 October 1941. Hitler, recalled him to be Inspector General of Panzer troops in February 1943 and after the 1944 Bomb Plot appointed him Chief of Staff in place of Zeitler. Germany’s military situation was hopeless and Guderian came too late. He retained the post, though constantly at odds with Hitler, until 21 March 1945, when he was finally dismissed. Guderian was a great military theorist and battlefield Commander, perhaps Germany’s greatest.