On two occasions he was deprived of his command in the Prussian army and he proposed marriage to the celebrated ballerina Marie Taglioni; consequently he was generally considered to be the "black sheep" of the family.

The marriage was unhappy and the couple had an only child: Charlotte (1868-1944) who married Prince Heinrich XVIII Reuss of Köstritz.

William took part in the Austro-Prussian War of 1866 as a major general in command of a cavalry brigade in the First Army.

He managed, with difficulty, to secure a command in the Prussian Army during the Franco-Prussian War, leading the 6th Cavalry Division, but he was wounded on 9 September 1870 in Laon.

As a result, he was long absent from the front and he showed a great lack of energy at the Battle of Le Mans.