 Two former members, the Grand Duchy of Luxembourg and the Duchy of Limburg, had the Dutch king as their head of state (as "Grand Duke of Luxembourg" and "Duke of Limburg").To clarify the position in the wake of the death of the Confederation further, the Treaty of London affirmed the end of the Confederation and stated that Limburg was henceforth to be considered with all its "territories" an "integral part of the Kingdom of the Netherlands".The independent Grand Duchy of Luxembourg, still linked to the Netherlands by a personal union, would rejoin the newly re-established German customs union, the "Zollverein", in which it would remain until 1 January 1919, long after the personal union had ended (1890).