on 16 february 1764 she was married by proxy at madrid to archduke peter leopold, the second son of emperor francis i and empress maria theresa of austria, and the heir apparent to the grand duchy of tuscany. the next year, on 5 august, she married him in person at innsbruck. only a few days later, the death of emperor francis made maria luisa's husband the new grand duke of tuscany, and the newly married couple moved to florence, where they would live for the next twenty-five years.