His wife's relatives intervened because of his lavish lifestyle and he had to promise not to mortgage any assets from her dowry without their consent.

They had at least three children: two sons, Rudolf IV and Hugo, who succeeded him, and a daughter, Ursula, who became the second wife of Count James Truchseß of Waldburg.

As William was constantly in debt and the pressure of his creditors increased, he found eventually that he could only keep his ancestral lands in the family by abdicating in favour of his sons.

Via his cousin John of Freiburg-Neuchâtel, William gained access to the court of the Duke of Burgundy in Dijon.

After the Swiss defeated the Austrians in the Battle of St. Jakob an der Sihl in 1443, the Emperor sent William to King Charles VII of France to plea for help.