In March 1815, amidst the turmoil of the Hundred Days, the Sovereign Prince William of Orange and Nassau adopted the style of "King of the Netherlands". Following Napoleon's second defeat at the Battle of Waterloo in June 1815, the Vienna Congress supplied international recognition of William's unilateral move. The new King of the Netherlands was also made Grand Duke of Luxembourg, a part of the Kingdom that was, at the same time, a member state of the German Confederation.