BOLESLAUS I., called "The Great," king of Poland (d. 1025), was the son of Mieszko, first Christian prince of Poland, and the Bohemian princess Dobrawa, or Bona, whose chaplain, Jordan, converted the court from paganism to Catholicism. He succeeded his father in 992. A born warrior, he speedily raised the little struggling Polish principality on the Vistula to the rank of a great power. In 996 he gained a seaboard by seizing Pomerania, and subsequently took advantage of the troubles in Bohemia to occupy Cracow, previously a Czech city. Like his contemporaries, Stephen of Hungary and Canute of Denmark, Boleslaus recognized from the first the essential superiority of Christianity over every other form of religion, and he deserves with them the name of "Great" because he deliberately associated himself with the new faith. Thus despite an inordinate love of adventure, which makes him appear rather a wandering chieftain than an established ruler, he was essentially a man of insight and progress. He showed great sagacity in receiving the fugitive Adalbert, bishop of Prague, and when the saint suffered martyrdom at the hands of the pagan Slavs (April 23, 997), Boleslaus purchased his relics and solemnly laid them in the church of Gnesen, founded by his father, which now became the metropolitan see of Poland. It was at Gnesen that Boleslaus in the year 1000 entertained Otto III. so magnificently that the emperor, declaring such a man too worthy to be merely princeps, conferred upon him the royal crown, though twenty-five years later, in the last year of his life, Boleslaus thought it necessary to crown himself king a second time. On the death of Otto, Boleslaus invaded Germany, penetrated to the Elbe, occupying Stralsund and Meissen on his way, and extended his dominions to the Elster and the Saale. He also occupied Bohemia, till driven out by the emperor Henry IV. in 1004. The German war was terminated in 1018 by the peace of Bautzen, greatly to the advantage of Boleslaus, who retained Lusatia. He then turned his arms against Jaroslav, grand duke of Kiev, whom he routed on the banks of the Bug, then the boundary between Russia and Poland. For ten months Boleslaus remained at Kiev, whence he addressed triumphant letters to the emperors of the East and West. At his death in 1025 he left Poland one of the mightiest states of Europe, extending from the Bug to the Elbe, and from the Baltic to the Danube, and possessing besides the overlordship of Russia. But his greatest achievement was the establishment in Poland of a native church, the first step towards political independence.
See J.N. Pawlowski, St Adalbert (Danzig, 1860); Chronica Nestoris (Vienna, 1860); Heinrich R. von Zeissberg, Die Kriege Kaiser Heinrichs II. mit Herzog Boleslaw I. (Vienna, 1868).
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)