German prince, a member of the Roman Catholic branch of the House of Hohenzollern, he adopted the surname Prinz von Hohenzollern-Emden in 1933.
He was the second son of Wilhelm, Prince of Hohenzollern and Princess Maria Teresa of Bourbon-Two Sicilies. He had a twin brother, Friedrich, Prince of Hohenzollern, who was born a few minutes before he was.
During World War I Franz Joseph served in Germany’s Imperial Navy as the second torpedo officer on the light cruiser SMS Emden at the Battle of Cocos. The SMS Emden had an extraordinary record capturing British ships, and as a result all those who served on her, including Franz Joseph, were given the right to add the ship’s name to the end of their surnames. Since Germany had converted titles of nobility into family names in 1919, he became Franz Joseph Prinz von Hohenzollern-Emden.
In 1925 Franz Joseph wrote a book recording his naval service, Emden: Meine Erlebnisse auf S.M Schiff Emden (Leipzig: Eckstein, 1925), translated into English and published as Emden: My Experiences in S.M.S. Emden.
In 1933 Franz Joseph became a member of the SS and on 1 April 1936 he became as full member of the Nazi party.
From 1939 to 1944 Franz Joseph commanded a marine flak battery at the Cuxhaven naval base.
On 25 May 1921, Franz Joseph married his second cousin Princess Maria Alix of Saxony, a daughter of Friedrich August III of Saxony and Archduchess Luise, Princess of Tuscany. His twin brother was married to Maria Alix’s sister, Princess Margarete Karola of Saxony.
Franz Joseph and Maria Alix had four children. He died on 3 April 1964 at age 72 in Tübingen, Baden-Württemberg.

Link to Wikipedia biography