Established in 963, Luxembourg was elevated to the status of a grand duchy in 1815 and became a part of the Kingdom of the Netherlands following the Congress of Vienna. In 1839, when Belgium asserted its independence from the Netherlands, Luxembourg ceded over half of its land to Belgium but achieved greater autonomy within the Kingdom of the Netherlands. Luxembourg attained full sovereignty in 1867, committing to a stance of permanent neutrality. Occupied by Germany during both World Wars, its neutrality was relinquished in 1948 when it became a member of the Benelux Customs Union, subsequently joining NATO the next year. In 1957, Luxembourg emerged as one of the original six nations of the EEC (which evolved into the EU), and in 1999, it became part of the euro currency area.