After the war Model remained in the army and in 1930 was appointed head of the war ministry's technical warfare section. A great supporter of mechanized warfare, Model was placed in charge of the department responsible for creating new and improved weapons.
In 1939 Model took part in the invasion of Poland and served under Ernst Busch in the 16th Army in the Western Offensive during 1940. The following year he served under Heinz Guderian during Operation Barbarossa and in October 1941, Model was promoted to commander of 41st Panzer Corps.
On 14th January 1942, Model was transferred to the 9th Army. Under attack from Russian partisans, Model asked Hitler for a panzer corps to help protect his troops. Hitler refusal led to a heated argument and Model told him that a commander at the front was in a better position to develop strategy than people in the rear studying maps. Hitler, who respected Model as a soldier eventually gave in and gave him the troops he demanded.
Despite his disagreements with Adolf Hitler Model was promoted to general in February 1942. While retreating from the Soviet Union in 1943 Model gave orders for the systematic destruction of towns and their populations that resulted in him being labeled as a war criminal.
In March 1944 Model replaced Erich von Manstein as Commander in Chief in the Soviet Union. In August 1944 he was transferred to the Western Front where he succeeded Gunther von Kluge. However, after 18 days Hitler had second thoughts about Model and he lost his command to Gerd von Rundstedt.
In 1945 Model and what was left of his troops had to defend the Ruhr. Once again he clashed with Adolf Hitler when he refused to let him retreat to the Rhine. Aware that he would be tried as a war criminal if he surrendered, Walther Model committed suicide on 21st April 1945.