Franckenberg was born in (Groß-Glogau, Silesia, into an ancient family devotedly attached to the Habsburg Monarchy of Austria, and which remained so after the conquest of Silesia by Frederick II of Prussia in 1740. Although he was the sole male heir of his family and assured of the protection of Empress Maria Theresa, he decided, when quite young, to become a priest. He attended the Jesuit college of his native city, went later to the University of Breslau, and thence to the German College at Rome, where he obtained the degrees of Doctor of Theology, and of Canon law, and was ordained priest on 10 August 1749.