Sixtus of Bourbon-Parma, Prince definition of Sixtus of Bourbon-Parma, Prince in the Free Online Encyclopedia.

Sixtus of Bourbon-Parma, Prince, 1886–1934, son of Robert, last duke of Parma. While serving as an officer in the Belgian army, he was the intermediary for his brother-in-law, Emperor Charles I Charles I, 1887–1922, last emperor of Austria and, as Charles IV, king of Hungary (1916–18); son of Archduke Otto and grandnephew and successor of Emperor Francis Joseph. He married Zita of Bourbon-Parma.
..... Click the link for more information. of Austria-Hungary, in Charles's secret attempt to negotiate peace with the Allies in 1917. The effort came to nothing, but in Apr., 1918, the French government, in retaliation for attacks made by the Austrian foreign minister Czernin Czernin, Ottokar, Graf (ô`tōkär gräf chĕr`nĭn), 1872–1932, Austro-Hungarian foreign minister.
..... Click the link for more information. , published a letter written by Charles to Sixtus. The letter justified French claims to Alsace-Lorraine, and its publication caused acute embarrassment to the Austrian government.