The marriage of Maria Theresa and Francis of Lorraine came with quite a few consequences. Francis had succeeded his father as Duke of Lorraine in 1729, but as part of a solution to the War of the Polish Succession, Emperor Charles VI asked that Francis gave away Lorraine to the deposed King of Poland for his lifetime. For his part, Francis would be compensated by being given the Grand Duchy of Tuscany. It was a difficult decision for Francis, and he even hesitated during the betrothal ceremony and put down his quill before eventually signing the documents. His family had ruled Lorraine 959; it would the end of an era. Francis ceased being Duke of Lorraine on 9 July 1737.
Lorraine was founded in 959 following the division of Lotharingia into two separate duchies, Upper and Lower Lorraine and the capital was Nancy. While the lower Duchy was dismantled, Upper Lorraine became known as the Duchy of Lorraine. Lower Lorraine fell apart into many independent fiefdoms, such as the County of Guelders, Holland and Cleves.
The Duchy of Lorraine was given to Stanisław Leszczyński, former King of Poland with the understanding that it would come to the French crown after his death. His daughter, Marie Leszczyńska, was married to Louis XVof France. Upon Stanislaw’s death in 1766, Lorraine was annexed and became a province of France. The House of Habsburg-Lorraine continued to call themselves (titular) Dukes of Lorraine.