Panzer Group Kleist was the first operational formation of several Panzer corps in the Wehrmacht. Created for the Battle of France on 1 March 1940; it was named after its commander Ewald von Kleist. Panzer Group Kleist played an important role in the Battle of Belgium. Panzer corps of the Group broke through the Ardennes and reached the sea, forming a huge pocket, containing several Belgian, British, and French armies. When the armistice was signed, the Group was deployed in occupied France, being renamed to Panzer Group 1 ("Panzergruppe 1") in November. In April 1941, Panzer Group 1 took part in the invasion of Yugoslavia as part of Field Marshal Maximilian von Weichs's Second Army.