6th Army would join the 6th SS Panzer Army in its thrust southeast to the Danube, then turn north to cover the flank of “Frühlingserwachen”. The 2nd Panzer Army's “Eisbrecher” would advance from an area southwest of Lake Balaton and progress towards Kaposvár to engage the Soviet 57th Army. All this time, the Hungarian Third Army would hold the area west of Budapest along the Vértes Mountains. Soviet preparation Interrupted Soviet offensive preparations On 17 February 1945, the Soviet High Command (Stavka) instructed the 2nd and 3rd Ukrainian Fronts to prepare for an offensive towards Vienna which would begin on March 15. However, from 17 to 18 February, the 2nd Ukrainian Front noticed the 1st SS Panzer division Leibstandarte and the 12th SS Panzer division Hitlerjugend fighting at the Garam River (S:Hron) during the German Operation Southwind. Knowing that German Panzer divisions were not created for defensive purposes, the Soviet Fronts in Hungary became suspicious of the enemy's intentions. Prisoners taken during Operation Southwind testified that the Germans were in fact preparing to gather a large offensive force. By 20 February, the Soviet fronts in Hungary began to understand what the Germans planned to do. The security of the lands West of the River Danube, particularly in the south which held the Hungarian oil fields, was the Germans' main priority at this stage of the war. Soviet defensive preparations As the 2nd Ukrainian Front held the territory of Budapest and the lands north of the Hungarian capital, defensive preparations in this sector were not paid much attention due to the lower likelihood of attack, but this was not the same in the south. 3rd Ukrainian Front marshal Fyodor Tolbukhin ordered his armies to prepare for a German offensive on his entire Front, preparation of which would have to be completed no later then 3 March. To ensure sufficient supply of war materials and fuel, stockpiles were set up on either side of the Danube, a ferry was put into use and additional temporary bridges and gas pipelines were built on the Danube River. Tolbukhin's plan was to initially slow down the German advance to rob their offensive of momentum, then begin grinding down the attacking armies, then initiate the planned Soviet offensive to finish off the remaining German forces. This plan, along with the strategic deployment of the Soviet forces, was quite similar to that of the Battle of Kursk,