Ferdinand Karl was the third son of Archduke Charles Louis of Austria and Princess Maria Annunciata of Bourbon-Two Sicilies.

Archduke Franz Ferdinand, whose assassination at Sarajevo on 28 June 1914 launched World War I, was his elder brother.

Unlike his brother, he did so without the emperor's knowledge or consent, having eloped two years before the marriage was revealed publicly.

On 6 August 1911 he renounced his rights and titles as a dynast of the House of Habsburg and assumed the name of "Ferdinand Burg",[1] at the demand of Emperor Franz Joseph.

Henceforth he absented himself from the Viennese court and lived in Tyrol.