 He was born as a son of Princess Sophie of Saxe-Coburg-Saalfeld and Count Emmanuel von Mensdorff-Pouilly, a member of the House of Mensdorff-Pouilly.He entered the Austrian army in 1829, and he was promoted to captain in 1836 and major in 1844.In 1848–49, he fought in the First Italian War of Independence and against the Hungarian Revolution of 1848.