Born 939 of a noble Bohemian family; died 997.
The people of Hungary were just then turning towards Christianity. Adalbert went among them as a missionary, and probably baptized King Geysa and his family, and King Stephen. He afterwards evangelized the Poles, and was made Archbishop of Gnesen. But he again relinquished his see, and set out to preach to the idolatrous inhabitants of what is now the Kingdom of Prussia. Success attended his efforts at first, but his imperious manner in commanding them to abandon paganism irritated them, and at the instigation of one of the pagan priests he was killed. This was in the year 997.
His feast is celebrated 23 April, and he is called the Apostle of Prussia. Boleslas I, Prince of Poland, is said to have ransomed his body for an equivalent weight of gold. He is thought to be the author of the war-song, “Boga-Rodzica”, which the Poles used to sing when going to battle.
T.J. CAMPBELL (Catholic Encyclopedia)