text: When Frederick ascended the throne as the third "King in Prussia" in 1740, his realm consisted of scattered territories, including Cleves, Mark, and Ravensberg in the west of the Holy Roman Empire; Brandenburg, Hither Pomerania, and Farther Pomerania in the east of the Empire; and the Kingdom of Prussia, the former Duchy of Prussia, outside of the Empire bordering the Polish–Lithuanian Commonwealth. He was titled King in Prussia because his kingdom included only part of historic Prussia; he was to declare himself King of Prussia after the First Partition of Poland in 1772.
  Reign
  War of the Austrian Succession
  When Frederick became king, he faced vulnerably disconnected holdings with a weak economic base. To strengthen Prussia's position, he fought wars mainly against Austria, whose Habsburg dynasty had reigned as Holy Roman Emperors continuously since the 15th century. Thus, upon succeeding to the throne on 31 May 1740, Frederick declined to endorse the Pragmatic Sanction of 1713, a legal mechanism to ensure the inheritance of the Habsburg domains by Maria Theresa of Austria, daughter of Holy Roman Emperor Charles VI. Upon the death of Charles VI on 29 October 1740, Frederick disputed the 23-year-old Maria Theresa's right of succession to the Habsburg lands, while simultaneously asserting his own right to the Austrian province of Silesia based on a number of old, though ambiguous, Hohenzollern claims to parts of Silesia.