[1] At the outbreak of the War of Polish Succession against the French, he served again under Eugene of Savoy on the Rhine.
During the War of Austrian Succession, he forged a military alliance between Austria, Britain and the Netherlands.
Another child was Marie Victoire Pauline d'Arenberg, wife of August Georg Simpert, Margrave of Baden-Baden.
A third one, Marie Flore, was the wife of Jean Charles Joseph, Count of Merode, Marquis of Deynze.
Together with this son-in-law and the Duke of Ursel, Leopold became one of the co-directors of the Théatre de la Monnaie in 1750–1752.