Frederick recognised at once that the siege must be abandoned, and with it his whole enterprise. He admitted that he had lost the superiority over the Austrians which he had gained in 1757. Threatening to imprison and cashier officers who should make faces or say that all was lost, he slipped cleverly past Daun’s left into Bohemia, and for a month remained there at his ease. Then he sped swiftly northward. On August 22, 1758, he was at Cüstrin dictating a fresh testament on the eve of the encounter with a new and gigantic foe. In estimating Frederick’s prospects for the campaign of 1758, no account has yet been taken of Russia. The action of the Muscovite forces was proverbially uncertain and of necessity slow. It was possible that they would not influence the main struggle at all, or that Frederick’s plan of aggression in the South would be accomplished before they had time to become formidable. Since the New Year, however, storm-clouds had been massing to the north-eastward. It is fortunately no part of our task to peer behind them into the dark secrets of the Russian court. Suffice it to say that Elizabeth still lived, and that so long as she remained on the throne peace with Prussia was impossible. Her armies might be ill-found and her ministers corrupt, but it would be strange if the mistress of Russia proved too weak to wound Frederick in his ill-guarded flank beyond the Oder. Fermor received the chief command of an army 34,000 strong. In January, 1758, he overran Ost-Preussen and forced the inhabitants to swear fealty to the Czarina. In February Königsberg was illuminated in honour of Russian royalty. Frederick avenged the first offence by reprisals upon the Saxons, the second by withdrawing his favour for ever from the polluted province. His power of self-restraint is attested by the fact that he attempted nothing by way of rescue. He calculated dispassionately that Fermor’s advance would at best be slow, that a broad expanse of barren Polish territory separated the invader from the rest of the Prussian dominions, and that offensive action in the South was more likely to be profitable than defensive in the North. Königsberg had been a Russian city for more than three months when Frederick dashed into Moravia.