The France–Germany border border can be traced back to the 17th century, and the various treaties following the Thirty Years' War (1618–1648), starting with the Treaty of Westphalia (1648) and the Treaty of Nijmegen (1678–1679), marking the Rhine as the frontier between the Kingdom of France, and the different German states. The actual border was determined in the Congress of Vienna in 1815. The border then changed after the French defeat during the Franco-Prussian War (1870-1871), where the French Third Republic was forced to yield Alsace-Lorraine to the new German Empire in 1871.