“Pragmatic Sanction of Emperor Charles VI, (April 19, 1713), decree promulgated by the Holy Roman emperor Charles VI with the intent that all his Habsburg kingdoms and lands descend as an integral whole without partition. It stipulated that his undivided heritage go to his eldest son, should he have one, or, failing a son, to his eldest daughter and then, if she should die without issue, to his deceased brother Joseph I’s daughters and their descendants.” (http://global.britannica.com/topic/Pragmatic-Sanction-of-Emperor-Charles-VI)
The War of Austrian Succession began when Frederick II of Prussia invaded Silesia, on 16 December 1740. Maria Theresa, Empress of the Holy Roman Empire, sought help from the European kings who had recognized respect for her father. Nevertheless, she was not offered military support as she expected.
The Treaty of Aachen (Aix-la-Chapelle), signed on October 18, 1748, ended the "War of the Austrian Succession"; But the decision of Empress Maria Theresa of Austria to seek recovery of Silesia, led to the Seven Years' War. Maria Teresa had the support of France, Russia, Saxony and Sweden against Prussia and Britain who were allies by the Treaty of Westminster, signed in January 1756.