Turning to a more active life, he accompanied the emperor Maximilian I to Italy in 1508, and after his return spent some time in Hungary.
In December, Frederick, grand master of the Teutonic Order, died, and Albert, joining the order, was chosen as his successor early in 1511 in the hope that his relationship to his uncle, his mother's brother, Sigismund I Jagiello Grand Duke of Lithuania and king of Poland, would facilitate a settlement of the disputes over east Prussia, which had been held by the order under Polish suzerainty since 1466 (which was not recognized by pope or emperor).
The new master, however, showed no desire to be conciliatory, and as war appeared inevitable, he made strenuous efforts to secure allies, and carried on tedious negotiations with the emperor Maximilian I.
The ill-feeling, influenced by the ravages of members of the order in Poland, culminated in a struggle which began in December 1519. During the ensuing year Prussia was devastated, and Albert consented early in 1521 to a truce for four years.
The dispute was referred to the emperor Charles V. and other princes, but as no settlement was reached the master continued his efforts to obtain help in view of a renewal of the war. For this purpose he visited the diet of Nuremberg in 1522, where he made the acquaintance of the reformer, [Andreas Osiander]?, by whose influence he was won over to the side of the new faith.
He then journeyed to Wittenberg?, where he was advised by Martin Luther to cast aside the senseless rules of his order, to marry, and to convert Prussia into an hereditary duchy for himself. This proposal, which commended itself to Albert, had already been discussed by some of his relatives; but it was necessary to proceed cautiously, and he assured Pope Adrian VI that he was anxious to reform the order and punish the knights who had adopted Lutheran doctrines. Luther for his part did not stop at the suggestion, but in order to facilitate the change made special efforts to spread his teaching among the Prussians, while Albert's brother, George, prince of Ansbach, laid the scheme before Sigismund of Poland. After some delay the king assented to it provided that Prussia were held as a Polish fief; and after this arrangement had been confirmed by a treaty made at Cracow, Albert was invested with the duchy by Sigismund for himself and his heirs on the 10th of February 1525.
The estates of the land then met at Koenigsberg and took the oath of allegiance to the new duke, who used his full powers to forward the doctrines of Luther. This transition did not, however, take place without protest. Summoned before the imperial court of justice, Albert refused to appear and was placed under the ban; while the order, having deposed the grand master, made a feeble effort to recover Prussia. But as the German princes were either too busy or too indifferent to attack the duke, the agitation against him soon died away.
In imperial politics Albert was fairly active. Joining the league of Torgau in 1526, he acted in unison with the Protestants, and was among the princes who banded themselves together to overthrow Charles V after the issue of the Interim in May 1548. For various reasons, however, poverty and personal inclination among others, he did not take a prominent part in the military operations of this period.
The early years of Albert's rule in Prussia were fairly prosperous. Although he had some trouble with the peasantry, the lands and treasures of the church enabled him to propitiate the nobles and for a time to provide for the expenses of the court.
He did something for the furtherance of learning by establishing schools in every town and by giving privileges to serfs who adopted a scholastic life. In 1544, in spite of some opposition, he founded the Koenigsberg University, where he appointed his friend Osiander to a professorship in 1549.
This step was the beginning of the troubles which clouded the closing years of Albert's reign. Osiander's divergence from Luther's doctrine of justification by faith involved him in a violent quarrel with Melanchthon?, who had adherents in Koenigsberg, and these theological disputes soon created an uproar in the town. The duke strenuously supported Osiander, and the area of the quarrel soon broadened. There were no longer church lands available with which to conciliate the nobles, the burden of taxation was heavy, and Albert's rule became unpopular.
Albrecht paid for the printing of the Astronomical Tables ("Prutenische Tafeln")compiled by Erasmus Reinhold.
After Osiander's death in 1552 he favoured a preacher named John Funck, who, with an adventurer named Paul Scalich, exercised great influence over him and obtained considerable wealth at the public expense. The state of turmoil caused by these religious and political disputes was increased by the possibility of Albert's early death and the necessity in that event for a regency owing to the youth of his only son, Albert Frederick. The duke was consequently obliged to consent to a condemnation of the teaching of Osiander, and the climax came in 1566 when the estates appealed to Sigismund II,[Albrecht von Brandenburg- Ansbach- Prussia's cousin, the son of Sigismund I and Elisabeth Habsburg,Grand Duke of Lithuania and] king of Poland, who sent a commission to Koenigsberg. Scalich saved his life by flight, but Funck was executed; the question of the regency was settled; and a form of Lutheranism was adopted, and declared binding on all teachers and preachers.
Virtually deprived of power, the duke lived for two years longer, and died at Tapiau on the 20th of March 1568. In 1526 he had married Dorothea, daughter of [Frederick I]?, king of Denmark, and after her death in 1547, Anna Maria, daughter of Eric I., duke of Brunswick?.
Albert was a voluminous letterwriter, and corresponded with many of the leading personages of the time.
For switching to Protestantism Albrecht had been put under ban by the pope.The Habsburg imperial rulers of the Holy Roman Empire continued claiming the office of grandmaster of the Teutonic Knights as administrators of Prussia.
In 1891 a statue was erected to his memory at Koenigsberg.
See History of Germany See Brandenburg,Prussia