The history of the Franco-German War and Alsace Lorraine Alsace is a peculiar history of Franco-German feud. Before the 30-year war, Alsace Lorraine belonged to Germany, and after the 30-year war, it belonged to France. In the Franco-Prussian War, Alsace Lorraine returned to Germany again, but in World War I, France defeated Germany and regained Alsace Lorraine. During World War II, Germany merged Alsace Lorraine into the empire again, and after World War II, Alsace Lorraine was merged into France again as a province of France.