Belgium felt he had collaborated with Germany during the war. The Belgian Congo gained independence in 1960 during the Congo Crisis; Ruanda-Urundi followed with its independence two years later. Belgium joined NATO as a founding member and formed the Benelux group of nations with the Netherlands and Luxembourg. Belgium became one of the six founding members of the European Coal and Steel Community in 1951 and of the European Atomic Energy Community and European Economic Community, established in 1957. The latter has now become the European Union, for which Belgium hosts major administrations and institutions, including the European Commission, the Council
Monarchy of the Netherlands old republic as "sovereign prince". In 1815, after Napoleon escaped from Elba, William Frederick raised the Netherlands to the status of a kingdom and proclaimed himself King William I. As part of the rearrangement of Europe at the Congress of Vienna, the House of Orange-Nassau was confirmed as rulers of the Kingdom of the Netherlands, enlarged with what are now Belgium and Luxembourg. At the same time, William became hereditary Grand Duke of Luxembourg in exchange for ceding his family's hereditary lands in Germany to Nassau-Weilburg and Prussia. The Grand Duchy of Luxembourg was a part of the Netherlands (until