At the end of 1944 the Germans still held the western half of Poland, and their front was still 200 miles east of where it had been at the start of the war in 1939. The Germans had checked the Soviets’ summer offensive and had established a firm line along the Narew and Vistula rivers southward to the Carpathians, and in October they repelled the Red Army’s attempted thrust into East Prussia. Meanwhile, however, the Soviet left, moving up from the eastern Balkans, had been gradually pushing around through Hungary and Yugoslavia in a vast flanking movement; and the absorption of German forces in opposing this side-door approach detracted considerably from the Germans’ capacity to maintain their main Eastern and Western fronts.

The Soviet high command was now ready to exploit the fundamental weaknesses of the German situation. Abundant supplies for their armies had been accumulated at the railheads. The mounting stream of American-supplied trucks had by this time enabled the Soviets to motorize a much larger proportion of their infantry brigades and thus, with the increasing production of their own tanks, to multiply the number of armoured and mobile corps for a successful breakthrough.

Before the end of December ominous reports were received by Guderian—who, in this desperately late period of the war, had been made chief of the German general staff. German Army intelligence reported that 225 Soviet infantry divisions and 22 armoured corps had been identified on the front between the Baltic and the Carpathians, assembled to attack. But when Guderian presented the report of these massive Soviet offensive preparations, Hitler refused to believe it, exclaiming: “It’s the biggest imposture since Genghis Khan! Who is responsible for producing all this rubbish?”

If Hitler had been willing to stop the Ardennes counteroffensive in the west, troops could have been transferred to the Eastern Front; but he refused to do so. At the same time he refused Guderian’s renewed request that the 30 German divisions now isolated in Courland (on the Baltic seacoast in Lithuania) should be evacuated by sea and brought back to reinforce the gateways into Germany. As a consequence, Guderian was left with a mobile reserve of only 12 armoured divisions to back up the 50 weak infantry divisions stretched out over the 700 miles of the main front.

The Soviet offensive opened on January 12, 1945, when Konev’s armies were launched against the German front in southern Poland, starting from their bridgehead over the Vistula River near Sandomierz. After it had pierced the German defense and produced a flanking menace to the central sector, Zhukov’s armies in the centre of the front bounded forward from their bridgeheads nearer Warsaw. That same day, January 14, Rokossovsky’s armies also joined in the offensive, striking from the Narew River north of Warsaw and breaking through the defenses covering this flank approach to East Prussia. The breach in the German front was now 200 miles wide.

On January 17, 1945, Warsaw was captured by Zhukov, after it had been surrounded; and on January 19 his armoured spearheads drove into Łódź. That same day Konev’s spearheads reached the Silesian frontier of prewar Germany. Thus, at the end of the first week the offensive had been carried 100 miles deep and was 400 miles wide—far too wide to be filled by such scanty reinforcements as were belatedly provided.

The crisis made Hitler renounce any idea of pursuing his offensive in the west; but, despite Guderian’s advice, he switched the 6th Panzer Army not to Poland but to Hungary in an attempt to relieve Budapest. The Soviets could thus continue their advance through Poland for two more weeks. While Konev’s spearheads crossed the Oder River in the vicinity of Breslau (Wrocław) and thus cut Silesia’s important mineral resources off from Germany, Zhukov made a sweeping advance in the centre by driving forward from Warsaw, past Poznań, Bydgoszcz, and Toruń, to the frontiers of Brandenburg and of Pomerania. At the same time Rokossovsky pushed on, through Allenstein (Olsztyn), to the Gulf of Danzig, thus cutting off the 25 German divisions in East Prussia. To defend the yawning gap in the centre of the front, Hitler created a new army group and put Heinrich Himmler in command of it with a staff of favoured SS officers. Their fumbling helped to clear the path for Zhukov, whose mechanized forces by January 31, 1945, were at Küstrin, on the lower Oder, only 40 miles from Berlin.

Zhukov’s advance now came to a halt. Konev, however, could still make a northwesterly sweep down the left bank of the middle Oder, reaching Sommerfeld, 80 miles from Berlin, on February 13, and the Neisse River two days later. The Germans’ defense benefited from being driven back to the straight and shortened line formed by the Oder and Neisse rivers. This front, extending from the Baltic coast to the Bohemian frontier, was less than 200 miles long. The menace of the Soviets’ imminent approach to Berlin led Hitler to decide that most of his fresh drafts of troops must be sent to reinforce the Oder; the way was thus eased for the crossing of the Rhine River by the American and British armies.

On February 13, 1945, the Soviets took Budapest, the defense of which had entailed the Germans’ loss of Silesia.