After the defeat of Napoleon in 1815, the Duchy of Luxembourg was restored. However, as the territory had been part of the Holy Roman Empire as well as the Habsburgian Netherlands in the past, both the Kingdom of Prussia and the United Kingdom of the Netherlands now claimed possession of the territory. At the Congress of Vienna the great powers decided that Luxembourg would become a member state of the newly formed German Confederation, but at the same time William I of the Netherlands, the King of the Netherlands, would become, in personal union, the head of state. To satisfy Prussia, it was decided that not only the Fortress of Luxembourg be manned by Prussian troops, but also that large parts of Luxembourgish territory (mainly the areas around Bitburg and St. Vith) become Prussian possessions. This marked the second time that the Duchy of Luxembourg was reduced in size, and is generally known as the Second Partition of Luxembourg. To compensate the Duchy for this loss, it was decided to elevate the Duchy to a Grand-Duchy, thus giving the Dutch monarchs the additional title of Grand-Duke of Luxembourg.