William Frederick, son of the last stadtholder, returned to the Netherlands in 1813 and proclaimed himself Sovereign Prince of the Netherlands. Two years later, the Congress of Vienna added the southern Netherlands to the north to create a strong country on the northern border of France. William Frederick raised this United Netherlands to the status of a kingdom and proclaimed himself as King William I in 1815. In addition, William became hereditary Grand Duke of Luxembourg in exchange for his German possessions. However, the Southern Netherlands had been culturally separate from the north since 1581, and rebelled. The south gained independence in 1830 as Belgium (recognised by the Northern Netherlands in 1839 as the Kingdom of the Netherlands was created by decree), while the personal union between Luxembourg and the Netherlands was severed in 1890, when William III died with no surviving male heirs. Ascendancy laws prevented his daughter Queen Wilhelmina from becoming the next Grand Duchess.