Career
William was an older brother of Ferdinand of Romania. His maternal first cousins included (among others) Carlos I of Portugal, Infante Afonso, Duke of Porto, Frederick Augustus III of Saxony, and Princess Maria Josepha of Saxony. Between 1880 and 1886, William was heir presumptive to the Romanian throne.
On 20 December 1886, he renounced the rights to succeed to the throne of the Kingdom of Romania.
On 27 June 1889, William married Princess Maria Teresa of Bourbon-Two Sicilies. Her parents were Prince Louis, Count of Trani and Mathilde Ludovika, Duchess in Bavaria.
Mathilde was the fourth daughter of Maximilian, Duke in Bavaria and Princess Ludovika of Bavaria. William and Maria Teresa had three children:
Augusta Victoria of Hohenzollern (19 August 1890 – 29 August 1966).
Married first Manuel II of Portugal and secondly Robert, Count Douglas.
Prince Frederick Victor of Hohenzollern (30 August 1891 – 6 February 1965). Married Princess Margarete Karola of Saxony. She was a daughter of Frederick Augustus III of Saxony and Archduchess Luise, Princess of Tuscany.
Prince Francis Joseph of Hohenzollern, adopted the title Prince of Hohenzollern-Emden (30 August 1891 – 3 April 1964).
William succeeded his father as Prince of Hohenzollern on 8 June 1905. On 20 January 1915, Wilhelm married secondly Princess Adelgunde of Bavaria.
She was a daughter of Ludwig III of Bavaria and Maria Theresia of Austria-Este. There were no children from this marriage.
His title was effectively abolished with the collapse of the German Empire in 1918.
He continued to use his princely surname anyway. Having become familiar with the situation in Romania, the 22-year-old William renounced all rights to the succession of the kingdom (since 1881) of Romania by a letter in French dated on 20 December 1886. In 1914, upon the death of king Carol I of Romania, William"s next brother Ferdinand succeeded in Romania.
7 March 1864 – 3 September 1869: His Serene Highness Prince William of Hohenzollern-Sigmaringen
3 September 1869 – 2 June 1885: His Serene Highness Prince William of Hohenzollern
2 June 1885 – 8 June 1905: His Serene Highness The Hereditary Prince of Hohenzollern
8 June 1905 – 23 September 1910: His Highness The Prince of Hohenzollern
23 September 1910 - 22 October 1927: His Royal Highness The Prince of Hohenzollern.