France–Germany relations of the further integration of the EU. They are sometimes described as the "twin engine" or "core countries" pushing for moves. A tram straddling the Franco-German border, across the river Rhine from Strasbourg to Kehl, was inaugurated on the 28th of April 2017 symbolising the strength of relation between the two countries. Both France and Germany track their history back to the time of Charlemagne, whose vast empire included most of the area of both modern-day France and Germany – as well as the Netherlands, Belgium, Luxembourg, Switzerland, Austria, Slovenia, and northern Italy. The death of Charlemagne's son Louis the
Belgium during the Leopold period. In 1908, this outcry led the Belgian state to assume responsibility for the government of the colony, henceforth called the Belgian Congo. A Belgian commission in 1919 estimated that Congo's population was half what it was in 1879. Germany invaded Belgium in August 1914 as part of the Schlieffen Plan to attack France, and much of the Western Front fighting of World War I occurred in western parts of the country. The opening months of the war were known as the Rape of Belgium due to German excesses. Belgium assumed control of the German colonies of