After some delay Sigismund assented to the offer, with the provision that Prussia should be treated as a Polish fiefdom; and after this arrangement had been confirmed by a treaty concluded at Kraków, Albert pledged a personal oath to Sigismund I and was invested with the duchy for himself and his heirs on 10 February 1525.

The Estates of the land then met at Königsberg and took the oath of allegiance to the new duke, who used his full powers to promote 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 proscribed, while the order elected a new Grand Master, Walter von Cronberg, who received Prussia as a fief at the imperial Diet of Augsburg.
As the German princes were experiencing the tumult of the Reformation, the German Peasants' War, and the wars against the Ottoman Turks, they did not enforce the ban on the duke, and 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 and plotted together to overthrow Charles V after the issue of the Augsburg 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 freeing serfs who adopted a scholastic life.
In 1544, in spite of some opposition, he founded Königsberg University, where he appointed his friend Andreas Osiander to a professorship in 1549.
Albert also paid for the printing of the Astronomical "Prutenic Tables" compiled by Erasmus Reinhold and the first maps of Prussia by Caspar Hennenberger.

Osiander's appointment 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 Philip Melanchthon, who had adherents in Königsberg, 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.

After Osiander's death in 1552, Albert favoured a preacher named Johann Funck, who, with an adventurer named Paul Skalić, exercised great influence over him and obtained considerable wealth at 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 need, should that happen, to appoint a regent, as his only son, Albert Frederick was still a mere youth.
The duke was forced to consent to a condemnation of the teaching of Osiander, and the climax came in 1566 when the Estates appealed to King Sigismund II Augustus of Poland, Albert's cousin, who sent a commission to Königsberg.
Skalić 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 more years, and died at Tapiau on 20 March 1568 of the plague, along with his wife.
Cornelis Floris de Vriendt designed his tomb within Königsberg Cathedral.

Albert was a voluminous letter writer, and corresponded with many of the leading personages of the time.
After some delay Sigismund assented to the offer, with the provision that Prussia should be treated as a Polish fiefdom; and after this arrangement had been confirmed by a treaty concluded at Kraków, Albert pledged a personal oath to Sigismund I and was invested with the duchy for himself and his heirs on 10 February 1525.
The Estates of the land then met at Königsberg and took the oath of allegiance to the new duke, who used his full powers to promote 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 proscribed, while the order elected a new Grand Master, Walter von Cronberg, who received Prussia as a fief at the imperial Diet of Augsburg. As the German princes were experiencing the tumult of the Reformation, the German Peasants' War, and the wars against the Ottoman Turks, they did not enforce the ban on the duke, and 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 and plotted together to overthrow Charles V after the issue of the Augsburg 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 freeing serfs who adopted a scholastic life. In 1544, in spite of some opposition, he founded Königsberg University, where he appointed his friend Andreas Osiander to a professorship in 1549. Albert also paid for the printing of the Astronomical "Prutenic Tables" compiled by Erasmus Reinhold and the first maps of Prussia by Caspar Hennenberger.
Osiander's appointment 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 Philip Melanchthon, who had adherents in Königsberg, 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.
After Osiander's death in 1552, Albert favoured a preacher named Johann Funck, who, with an adventurer named Paul Skalić, exercised great influence over him and obtained considerable wealth at 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 need, should that happen, to appoint a regent, as his only son, Albert Frederick was still a mere youth. The duke was forced to consent to a condemnation of the teaching of Osiander, and the climax came in 1566 when the Estates appealed to King Sigismund II Augustus of Poland, Albert's cousin, who sent a commission to Königsberg. Skalić 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 more years, and died at Tapiau on 20 March 1568 of the plague, along with his wife. Cornelis Floris de Vriendt designed his tomb within Königsberg Cathedral.
Albert was a voluminous letter writer, and corresponded with many of the leading personages of the time.
Albert, Duke of Prussia