Ludwig studied at the University of Leiden from 1769 and subsequently undertook his Grand Tour to London and Paris. In France he met, among others, the French philosophers Jean le Rond d'Alembert and Denis Diderot, who were some of the prominent figures of the Age of Enlightenment, and editors of the first modern encyclopedia. In 1773 he traveled with the German-born French writer and critic Friedrich Melchior Grimm to the court of Frederik the Great in Prussia, where his sister Frederica Louisa was married to the heir presumptive Frederick William. Finally, he traveled on to Russia, where in 1773 he attended the wedding of his second sister Wilhelmina Louisa in St. Petersburg to the heir to the Russian throne, Grand Duke Paul. As a Russian general Ludwig fought in 1774 in the Russo-Turkish War, and the same year he became freemason in the lodge "To the crowned flag "in Moscow.
