The Wends, in Prussia, were giving trouble, and the Scandinavians and Danes ravaged all the northern coast of Germany; but the boy emperor, without giving a thought to his immediate duty, hastened back to Italy in 997, took Crescentius prisoner and beheaded him, barbarously mutilated the rival Pope, and reinstated Gregory V. When the latter died, in 999, Otto made his own teacher, Gerbert of Rheims, Pope, under the name of Sylvester II. In spite of the reverence of the common people for the Papal office, they always believed Pope Sylvester to be a magician, and in league with the Devil. He was the most learned man of his day, and in his knowledge of natural science was far in advance of his time; but such accomplishments were then very rare in Italy, and unheard of in a Pope. Otto III. remained three years longer in Italy, dividing his time between pompous festivals and visits to religious anchorites. In the year 1000 he was recalled to Germany. His father's sister, Mathilde, who had governed the country as well as she was able, during his absence, was dead, and there were difficulties, not of a political nature (for to such he paid no attention), but in the organization of the Church, which he was anxious to settle. The Poles were converted to Christianity by this time, and their spiritual head was the Archbishop of Magdeburg; but now they demanded a separate and national diocese. This Otto granted to their Duke, or king, Boleslaw, with such other independent rights, that the authority of the German Empire soon ceased to be acknowledged by the Poles. He made a pilgrimage to the tomb of St. Adalbert of Prague, who was slain by the Prussian pagans, then visited Aix-la-Chapelle, where, following a half-delirious fancy, he descended into the vault where lay the body of Charlemagne, in the hope of hearing a voice, or receiving a sign, which might direct him how to restore the Roman Empire. [Sidenote: 1001.] The new Pope, Sylvester II., after Otto III.'s departure from Rome, found himself in as difficult a position as his predecessor, Gregory V. He was also obliged to call the Emperor to his aid, and the latter returned to Italy in 1001. He established his Court in a palace on Mount Aventine, in Rome, and maintained his authority for a little while, in spite of a fierce popular revolt. Then, becoming restless, yet not knowing what to do, he wandered up and down Italy, paid a mysterious visit to Venice by night, and finally returned to Rome, to find the gates barred against him. He began a siege, but before anything was accomplished, he died in 1002, as was generally believed, of poison. The nobles and the imperial guards who accompanied him took charge of his body, cut their way through a population in rebellion against his rule, and carried him over the Alps to Germany, where he was buried in Aix-la-Chapelle.