Born in 1902 in Prague, then part of Austria-Hungary, Mildenstein belonged to the lowest tier of the Austrian nobility and was brought up as a Roman Catholic. He had Austrian, Hungarian, Czech, and German citizenships.Joseph Verbovszky, Leopold von Mildenstein and the Jewish Question (Cape Western Reserve University, May, 2013), p. 7 He trained as an engineer and joined the Nazi Party in 1929, receiving the membership number 106,678. In 1932 he joined the SS, becoming one of the first Austrians to do so. According to Dieter Wisliceny, his former SS colleague, Mildenstein visited the Middle East, including British-administered Palestine, several times until 1935.Jacob Boas, "A Nazi Travels to Palestine" in History Today, Vol. 30, Issue 1 (1980), pp. 33–38 Pascal Bruckner, Steven Rendall, The Tyranny of Guilt: An Essay on Western Masochism (2010), p. 68 On 30 January 1933 Adolf Hitler came to power as Chancellor of Germany.William Shirer, The Rise and Fall of the Third Reich (New York: Simon & Schuster, 1960), , p. 184
