March, the Axis forces fighting under Operation Spring Awakening around Lake Balaton had a total of 230 operational tanks and 167 operational assault guns between their 17 divisions. A single fully equipped late 1944 Panzer division would officially have held no fewer than 136 tanks, meaning that by 10 March the entire offensive immediately surrounding Lake Balaton had enough tanks for only 1.7 Panzer divisions as opposed to the 11 which were in action. By the 14 March, Operation Spring Awakening was at risk of failure. The 6th SS Panzer Army was well short of its goals. The 2nd Panzer Army did not advance as far on the southern side of Lake Balaton as the 6th SS Panzer Army had on the northern side. Army Group E met fierce resistance from the Bulgarian First Army and Josip Broz Tito's Yugoslavian partisan army, and failed to reach its objective of Mohács. German losses were heavy. Heeresgruppe Süd lost 15,117 casualties in the first eight days of the offensive. On the 15 March, strength returns on this day show the Hohenstaufen with 35 Panther tanks, 20 Panzer IVs, 32 Jagdpanzers, 25 Sturmgeschützes and 220 other self-propelled weapons and armoured cars. 42% of these vehicles were damaged, under short or long-term repair. The Das Reich Division had 27 Panthers, 22 Panzer IVs, 28 Jagdpanzers and 26 Sturmgeschützes on hand (the number of those under repair is not available). Soviet counterattack – Vienna Offensive On 16 March, the Soviets forces counterattacked in strength. The Germans were driven back to the positions they had held before Operation Spring Awakening began. The overwhelming numerical superiority of the Red Army made any defense impossible, but Hitler believed victory was attainable. On 22 March, the remnants of the 6th SS Panzer Army withdrew towards Vienna. By 30 March, the Soviet 3rd Ukrainian Front crossed from Hungary into Austria. By 4 April, the 6th SS Panzer Army was already in the Vienna area desperately setting up defensive lines against the anticipated Soviet Vienna Offensive. Approaching and encircling the Austrian capital were the Soviet 4th and 6th Guards Tank, 9th Guards, and 46th Armies. The Soviet's Vienna Offensive ended with the fall of the city on 13 April. By 15 April, the remnants of the 6th SS Panzer Army were north of Vienna, facing the Soviet 9th Guards and 46th Armies. By 15 April, the depleted German 6th Army was