Louis based his claims on ancient, often long-forgotten, rights to the dependent territories stemming from the Middle Ages. He thus took advantage of the formal content of his alliance treaties with the German princes by claiming their land. Although there was no legal claim to it at all, Louis took Strasbourg as well as Casale. Louis also took most of what is now Luxembourg during the War of the Reunions, which was then part of the Holy Roman Empire, while it was distracted by an ongoing war with the Ottoman Empire.