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
Military history of Luxembourg the predominantly francophone western part of the country was transferred to Belgium. Luxembourg's independence was reaffirmed by the 1839 First Treaty of London and again by the 1867 Second Treaty of London, after the Luxembourg Crisis nearly led to war between Prussia and France. The King of the Netherlands remained Head of State as Grand Duke of Luxembourg, maintaining personal union between the two countries until 1890. At the death of William III, the Dutch throne passed to his daughter Wilhelmina, while Luxembourg (at that time restricted to male heirs by the Nassau Family Pact) passed to Adolph of Nassau-Weilburg.