of the Bulge, a significant counterattack against the western Allies through the Ardennes with the aim of reaching Antwerp while encircling the Allied armies in the area. The offensive began with an artillery barrage shortly before dawn on 16 December. Spearheading the attack were two panzer armies composed largely of Waffen-SS divisions. The battlegroups found advancing through the forests and wooded hills of the Ardennes difficult in the winter weather, but they initially made good progress in the northern sector. They soon encountered strong resistance from the US 2nd and 99th Infantry Divisions. By 23 December, the weather improved enough for Allied air forces to attack the German forces and their supply columns, causing fuel shortages. In increasingly difficult conditions, the German advance slowed and was stopped. Hitler's failed offensive cost 700 tanks and most of their remaining mobile forces in the west, as well as most of their irreplaceable reserves of manpower and materiel. During the battle, SS-Obersturmbannführer Joachim Peiper left a path of destruction, which included Waffen-SS soldiers under his command murdering American POWs and unarmed Belgian civilians in the Malmedy massacre. Captured SS soldiers who were part of Kampfgruppe Peiper were tried during the Malmedy massacre trial following the war for this massacre and several others in the area. Many of the perpetrators were sentenced to hang, but the sentences were commuted. Peiper was imprisoned for eleven years for his role in the murders. In the east, the Red Army resumed its offensive on 12 January 1945. German forces were outnumbered twenty to one in aircraft, eleven to one in infantry, and seven to one in tanks on the Eastern Front. By the end of the month, the Red Army had made bridgeheads across the Oder, the last geographic obstacle before Berlin. The western Allies continued to advance as well, but not as rapidly as the Red Army. The Panzer Corps conducted a successful defensive operation on 17–24 February at the Hron River, stalling the Allied advance towards Vienna. The 1st and 2nd SS Panzer Corps made their way towards Austria but were slowed by damaged railways. Budapest fell on 13 February. Hitler ordered Dietrich's 6th Panzer Army to move into Hungary to protect the Nagykanizsa oilfields and refineries, which he deemed the most strategically valuable fuel reserves on the Eastern Front. Frühlingserwachsen (Operation Spring Awakening), the final German offensive in the east, took place in early