advancing at full speed. Each seemed to outbid the other.
The rapid advances of Zhukov's tank armies were partly due to the simplicity and robust construction of the T-34 tank and its broad tracks, which could cope with snow, ice and mud. Even so, the mechanic's skills proved at least as important as cavalry dash, because field workshops could not keep up. 'Ah, what a life it was before the war,' a driver remarked to Grossman. 'There were plenty of spare parts then.' Once the weather cleared, Shturmovik fighter bombers, known to the Germans as 'Jabos' for Jagdbomber , were able to support the headlong advance, as Zhukov had promised his tank commanders. 'Our tanks move faster than the trains to Berlin,' boasted the ebullient Colonel Gusakovsky, who had blasted his way across the Pilica.
The small German garrison in Warsaw did not stand a chance. It consisted of engineer detachments and four fortress battalions - one of them was an 'ear battalion' made up of hearing casualties recycled back into service. The thrust of the 47th Guards Tank Brigade up to Sochaczew from the south and the encirclement of Warsaw from the north by the 47th Army meant that the garrison lost contact with its parent formation, the Ninth Army.
General Harpe's staff at Army Group 'A' warned OKH in Zossen on the evening of 16 January that they would not be able to hold the city. Colonel Bogislaw von Bonin, the head of the operations department, discussed the situation with Guderian. They decided to give army group headquarters a free hand in the decision, and Guderian signed the signals log with his usual 'G' in green ink. But in the Nachtlage , Hitler's midnight situation conference, the proposal to abandon Warsaw was reported to Hitler by one of his own staff before Guderian's deputy, General Walther Wenck, brought the subject up. Hitler exploded. 'You must stop everything!' he shouted. 'Fortress Warsaw must be held!' But it was already too late and radio communications had broken down. A few days later Hitler issued an order that every instruction sent to an army group had to be submitted to him first.
The fall of Warsaw led to another bitter row between Hitler and Guderian, who were still arguing over Hitler's decision to move the Grossdeutschland Corps. Guderian was even more furious to hear that Hitler was transferring the Sixth SS Panzer Army not to the Vistula front, but to Hungary. Hitler, however, refused to discuss it. The withdrawal from Warsaw was, in his eyes, a far more burning issue.
At the noon conference next day, 18 January, Guderian was given a public dressing-down, but worse was to follow. 'That evening,' recounted Colonel Baron von Humboldt of the OKH staff, 'it was Bonin's birthday. We were all standing round the map table with a glass of Sekt to congratulate him, when [General] Meisel, the second-in-command of the personnel department, arrived with two Oberleutnants armed with machine pistols. "Herr von Bonin," he said. "I must ask you to come with me."' Two others were arrested with Bonin, Lieutenant Colonel von Christen and Lieutenant Colonel von dem Knesebeck. They were taken off to the Prinz-Albrechtstrasse on Hitler's direct orders to be interrogated by the Gestapo.
Hitler saw the incident as yet another act of betrayal by the army. As well as sacking General Harpe, he also removed General von Luttwitz from command of the Ninth Army. But the truth was that his monstrous vanity could not allow him to lose a foreign capital, even one which he had totally destroyed. Guderian stood up for his three staff officers, insisting that he be interrogated too since the responsibility for the decision was entirely his. Hitler, longing to indict the general staff, took him at his word. At this most critical stage of the Vistula campaign, Guderian was subjected to hours of interrogation by Ernst Kaltenbrunner of the Reich Security Head Office, and Heinrich Müller, the chief of the Gestapo. The two more junior officers were released