Background
He was the eldest son of Ferdinand of Bavaria and his morganatic wife Maria Pettenbeckin.
He was the eldest son of Ferdinand of Bavaria and his morganatic wife Maria Pettenbeckin.
He was educated by the Jesuits at Ingolstadt (1601-1608), and at the Germanicum in Rome (1608-1614).
In 1621 Franz Wilhelm became manager of the governmental affairs of the Elector Ferdinand of Cologne, who appointed him president of his council and brought him to the Diet of Ratisbon in 1622. On 26 October 1625, he was elected Bishop of Osnabrück, receiving papal approbation 25 April 1626. Cardinal Eitel Friedrich, who succeeded them, endeavoured to restore the Catholic religion but soon died.
With the help of Johann Tserclaes, Count of Tilly, Franz Wilhelm took possession of his see on 12 March 1628, which had been occupied by Danish soldiers.
In 1631, he founded a university which, however, was destroyed by the Swedes in 1633. Franz Wilhelm was commissioned with the execution of the 1629 Edict of Restitution in Lower Saxony, and was elected later to the provostry of the collegiate church of Ss.
Cassius and Florentius in Bonn. He was chosen Prince-Bishop of Verden in 1630, Bishop of Minden in 1631, and appointed Vicar Apostolic of Bremen by Pope Innocent X in 1645.
In 1633 Osnabrück capitulated to the Swedes and Wartenberg had to yield his see to Gustavus of Wasaburg, an illegitimate son of Gustavus Adolphus.
During his forced exile, Franz Wilhelm, who had not yet received any of the major orders, was ordained priest and consecrated bishop at Ratisbon in 1636. In 1641 he went to Rome and upon his return was elected Coadjutor Bishop of Ratisbon cum jure successionis, succeeding on 9 April 1650. In the negotiations of the Peace of Westphalia from 1645-1648 Franz Wilhelm represented the Catholic electors.
On 18 December 1650, he took possession of the See of Osnabrück and worked to restore the Catholic religion.
On 5 April 1661, he was created cardinal-priest by Pope Alexander VII.