Luxembourg an independent state under the personal possession of William I of the Netherlands with a Prussian garrison to guard the city against another invasion from France. In 1839, following the turmoil of the Belgian Revolution, the purely Oil-speaking part of Luxembourg was ceded to Belgium and the Luxembourgish-speaking part (except the Arelerland, the area around Arlon) became what is the present state of Luxembourg. Luxembourg is a founding member of the European Union, OECD, United Nations, NATO, and Benelux. The city of Luxembourg, which is the country's capital and largest city, is the seat of several institutions and agencies of
Foreign relations of Belgium liberation of Belgium at the end of World War II. In March 1948 Belgium joined with France, Luxembourg, the Netherlands, and Britain in an agreement to establish a joint defense system. This agreement, known as the Treaty of Brussels, was a recognition that individual national responses to the threat of aggression were inadequate and that a united defense effort was necessary for mutual security. In 1948, after expressions of concern by several European states that the Treaty of Brussels was too limited in scope and effectiveness, the prime minister of Canada called for a mutual defense system comprising Western Europe