In 1497 the order lost its possessions in Sicily through the influence of the Pope and the King of Aragon, who combined to deprive it of them. It still retained a house at Venice, and some other property in Lombardy. In 1511 Albert de Brandenberg was elected grand master. He made strenuous efforts to procure the independence of the order, and solicited the aid of the Emperor to free it from the authority of Poland, but without success. The grand master refused the customary homage to the King of Poland, and, after fruitless negotiations, war was once more declared, which continued till 1521, when peace was concluded; one of the results of which was the separation of Livonia from the dominion of the order, and its erection into an independent state.
All this time the doctrines of Luther had been making progress and spreading among all classes in Prussia and Germany. In 1522 the grand master went to Nuremberg to consult with the Lutherans there, and shortly afterward he visited Luther himself at Wittenberg. Luther's advice was decided and trenchant. He poured contempt upon the rules of the order, and advised Albert to break away from it and marry. Melancthon supported Luther's counsels. Shortly after, Luther wrote a vigorous letter to the knights of the order, in which he maintained that it was of no use to God or man. He urged all the members to break their vow of celibacy and to marry, saying that it was impossible for human nature to be chaste in any other way, and that God's law, which commanded man to increase and multiply, was older than the decrees of councils and the vows of religious orders. At the request of the grand master he also sent missionaries into Prussia to preach the reformed doctrines. One or two bishops and many of the clergy accepted them, and they spread rapidly among the people. Services began to be said in the vulgar tongue, and images and other ornaments were pulled down in the churches, especially in the country districts.
In 1525 Albert met the King of Poland at Cracow, and formally resigned his office as grand master of the Teutonic order, making over his dominions to the King, and receiving from him in return the title of hereditary Duke of Prussia. Shortly afterward he followed Luther's advice, and married the princess Dorothea of Denmark. Many of the knights followed his example. The annals and archives of the order were transferred to the custody of the King of Poland, and were lost or destroyed during the troubles that subsequently came upon that kingdom.