Charles VI had no male heirs and with the Pragmatic Sanction of 1713 he ensured that all the titles held by him could be inherited by a woman. Charles VI sought the other European powers' approval, which he gained in exchange for various concessions. Regardless, after her father's death, Maria Theresa had to defend her inheritance from the coalition of Prussia, Bavaria, France, Spain, Saxony and Poland in the War of Austrian Succession, that broke out mere weeks after her coronation in 1740. She ultimately managed to defend her title, but paid for it with the loss of Silesia, which became a part of Prussia. That was the ended the unity of the Lands of the Bohemian Crown. In 1757 during the Seven Years' War, the Prussians invaded Bohemia again and laid siege to Prague, but subsequently lost the Battle of Kolín and were repelled. Maria Theresa wasn't able to regain Silesia and the war ended in a draw. She tried to follow the ideas of Enlightenment, she established compulsory secular primary schools, but also state censorship of books that were deemed to be against the Catholic religion. Because of her marriage to Francis Stephen of Lorraine, all of her children were considered to be members of a new joint House of Habsburg-Lorraine.