France long sought to attain and then preserve what it considered to be its "natural boundaries", which were the Pyrenees to the southwest, the Alps to the southeast, and the Rhine River to the northeast. These strategic claims led to the annexation of territories located west of the Rhine river in the Holy Roman Empire. What is now known as Alsace was progressively conquered by France under Louis XIII and Louis XIV in the 17th century, while Lorraine was incorporated from the 16th century under Henry II to the 18th century under Louis XV (in the case of the Three Bishoprics, as early as 1552). These border-changes, at the time, meant more or less that one ruler (the local princes and city-governments, with some remaining power of the Holy Roman Emperor) was exchanged for another (the King of France); it was the French revolution that turned what might have been called "the King of France's German territories" into parts of France proper.