The division was tasked with the protection of the oil fields at Ploiești, which were vital to the German war effort. They trained some Romanian officers in German Panzer tactics. Apart from training, the soldiers had nothing to do and became bored. In March 1941 Strachwitz was sent back to Cosel in Germany where a new replacement unit was to be founded. He returned via his home town and 24 hours later a telegram from Hube called him back. This was preceded by a series of events in Belgrade. On 25 March 1941, the government of Prince Paul of Yugoslavia had signed the Tripartite Pact, joining the Axis powers in an effort to stay out of World War II. This was immediately followed by mass protests in Belgrade and a military coup d'état led by Air Force commander General Dušan Simović. As a result, Hitler chose not only to support Mussolini's ambitions in Albania and in the Greco-Italian War but also to attack Yugoslavia. For this purpose the mobilized forces of 1st Panzer Grooup under the command of "Generaloberst" Ewald von Kleist were ordered to attack Belgrade in what would become the Invasion of Yugoslavia.