The appearance of Charles on the Russian frontier forced him to a definite resolution, and, in the spring of 1708, his emissaries appeared at Radoshkovitse, southeast of Grodno, where Charles had established his head-quarters. The King of Sweden's idea, at that decisive moment, would seem to have been to take advantage of the hetman's friendly inclination, to find his way into the heart of Russia, using the rich Southern Provinces as his base, to stir up, with Mazeppa's help, the Don Cossacks, the Astrakhan Tartars, and, it may have been, the Turks themselves, and thus attack the Muscovite power in the rear. Then Peter would have been forced back upon his last intrenchments, at Moscow or elsewhere, while General Luebecker, who was in Finland with fourteen thousand men, fell on Ingria and on St. Petersburg, and Leszcynski's Polish partisans, with General Krassow's Swedes, held Poland.
It was a mighty plan, indeed, but at the very outset it was sharply checked. Mazeppa insisted on certain conditions, and these conditions Charles thought too heavy. The hetman agreed that Poland should take the Ukraine and White Russia, and that the Swedes should have the fortresses of Mglin, Starodoub, and Novgorod-Sievierski, but he himself insisted on being apportioned Polotsk, Vitebsk, and the whole of Courland, to be held in fief. Thus the negotiations were delayed. Meanwhile Charles, perceiving that he was not strong enough to make a forward movement, made up his mind to send for Loewenhaupt, who was in Livonia, and who was to bring him sixteen thousand men and various stores. But the Swedish hero had not reckoned fairly with distance and with time. Many precious days, the best of the season, fled by before his orders could be obeyed. And, for the first time, he showed signs of uncertainty and irresolution which were all too quickly communicated to those under his command. Loewenhaupt grew slower than usual. Luebecker slackened his activity, and Mazeppa began to play his double game again: prudently preparing his Cossacks to revolt, in the name of the ancient customs, national privileges, and church laws, which Peter's reforms had infringed; fortifying his own residence at Batourin, and accumulating immense stores there, but still continuing to pay court to the Czar, wearing the German dress, flattering the sovereign's despotic taste by suggesting plans which would have annihilated the last vestiges of local independence, and accepting gifts sent him by Menshikoff.
And so the summer passed away. A winter campaign became inevitable, and the abyss which Peter's unerring eye had scanned began to gape.
It was not till June that Charles XII left Radoshkovitse, and marched eastward to Borisov, where he crossed the Berezina. Menshikoff and Sheremetief made an attempt to stop him, on July 3d, as he was crossing a small river called the Bibitch, near Holovtchin. A night manoeuvre, and a wild bayonet charge, led by the King himself, carried him once more to victory. The town of Mohilef opened its gates to the Swedes, but there Charles was forced to stay, and lose more time yet waiting for Loewenhaupt. He marched again, early in August, in a southerly direction, and his soldiers soon found themselves in the grip of one of Peter's allies. They were driven to support themselves by gathering ears of corn, which they ground between two stones. Sickness began to thin their ranks. Their three doctors, so the fierce troopers said, were "brandy, garlic, and death"! Loewenhaupt had reached Shklof, and was separated from the invading army by two streams, the Soja and the Dnieper, between which Peter had taken up his position. The Swedish general, after having successfully passed the Dnieper, was met at Liesna, on October 9th, by a force three times as large as his own, and Peter was able, on the following day, to report a complete victory to his friends: "8500 men dead on the field, without mentioning those the Kalmucks have hunted into the forest, and 700 prisoners!" According to this reckoning, Loewenhaupt, who could not have brought more than 11,000 troops into action, should have been left without a man; as a matter of fact, he reached Charles with 6700, after a flank march which all military experts consider a marvel. But, not being able to find a bridge across the Soja, he was forced to abandon his artillery and all his baggage, and he led his starving troops into a famine-stricken camp.
There was bad news, too, from Ingria, where Luebecker had also been defeated, losing all his baggage and three thousand first-class troops. Charles grew so disconcerted that he is reported to have confessed to Gyllenkrook, his quartermaster-general, that he was all at sea, and no longer had any definite plan. On October 22d he reached Mokoshin on the Desna, on the borders of the Ukraine, where he had expected to meet Mazeppa. But the old leader broke his appointment. He still desired to temporize and was loath to take any decisive resolution. He was driven to take one at last, by the Cossacks about him, who were alarmed at the idea of the Russians following the Swedes into the Ukraine. It would be far better, so they thought, to join the latter against the former. One of these Cossacks, Voinarovski, who had been sent by the hetman to Menshikoff, had returned with most terrifying news. He had overheard the German officers on the favorite's staff, speaking of Mazeppa and his followers, say: "God pity those poor wretches; to-morrow they will all be in chains!" Mazeppa, when he heard this report, "raged like a whirlwind," hurried to Batourin to give the alarm, and then crossed the Desna and joined the Swedish army.
It was too late. The popular sentiment, on which both he and Charles had reckoned to promote an insurrectionary movement, confused by the tergiversations and the ambiguous actions of the hetman, had quite gone astray and lost all consistency. All Mazeppa could reckon upon was a body of two thousand faithful troops; not enough even to defend Batourin, which Menshikoff snatched from him a few days later—thus depriving the Swedish army of its last chance of revictualling. When the fortresses of Starodoub and Novgorod-Sievierski closed their gates against him, the whole of the Ukraine slipped from the grasp of the turncoat chief and his new allies. His effigy was first hung and then dragged through the streets of Glouhof in Peter's presence; another hetman, Skoropadski, was appointed in his place, and then came winter—a cruel winter, during which the very birds died of cold.
By the beginning of 1709 Charles' effective strength had dwindled to nearly twenty thousand men. The Russians did not dare to attack him as yet, but they gathered round him in an ever-narrowing circle. They carried his advanced posts, they cut his lines of communication. The King of Sweden, to get himself mere elbow-room, was driven to begin his campaign in the month of January. He lost one thousand men and forty-eight officers in taking the paltry town of Wespjik (January 6th). By this time the game, in Mazeppa's view, was already lost, and he made an attempt to turn his coat again; offering to betray Charles into Peter's hands if Peter would restore him his office. The bargain was struck, but a letter from the old traitor, addressed to Leszcynski, chanced to fall into the Czar's hands, and made him draw back, in the conviction that Mazeppa was utterly unreliable.
In March, the near approach of the Swedish army, then advancing on Poltava, induced the Zaporoje Cossacks to join it. But the movement was a very partial one, and Peter soon put it down, by means of a series of military executions, mercilessly carried out by Menshikoff, and of various manifestoes against the foreign heretics, "who deny the doctrines of the true religion, and spit on the picture of the Blessed Virgin." The capture of Poltava thus became the last hope of Charles and his army. If they could not seize the town, they must all die of hunger.
The fortifications of the place were weak, but the besieging army was sorely changed from that which had fought under the walls of Narva. It had spent too long a time in fat quarters, in Saxony and Poland, to be fit to endure this terrible campaign. Like the Russian army at Narva, it was sapped by demoralization before it was called on to do any serious fighting. Even among the Swedish staff, and in the King's intimate circle, all confidence in his genius and his lucky star had disappeared.
His best generals, Rehnskold and Gyllenkrook, his chancellor Piper, and Mazeppa himself were against any prolongation of the siege, which promised to be a long one. "If God were to send down one of his angels," he said, "to induce me to follow your advice, I would not listen to him!" An ineradicable illusion, the fruit of the too easy victories of his early career, prompted him to undervalue the forces opposed to him. He knew, and would acknowledge, nothing of that new Russia, the mighty upstanding colossus, which Peter had at last succeeded in raising up in his path. According to some authorities, Mazeppa, in his desire to replace Batourin by Poltava, as his own personal appanage, encouraged him in this fatal resolution. But it may well have been that retreat had already become impossible.