He never ruled over his own principality, but from 17 December 1803 to 20 March 1806 he was titled Duke of Berg.

He was the second son and the fourth of eight children born to John, Count Palatine of Gelnhausen and his wife Wild- and Rhinegravine Sophie Charlotte of Salm-Dhaun.

[2] Wilhelm and Maria Anna had two children:[2] On 16 February 1799, the head of the House of Wittelsbach Charles Theodore, Elector of Bavaria died.

Duke Wilhelm died on 8 January 1837 in Landshut or Bamberg in the Kingdom of Bavaria.

[1][2] He was interred at the family burial crypt of the Dukes in Bavaria at Tegernsee Abbey.