George William, 1597–1640, elector of Brandenburg (1619–40). Mild and irresolute, he was a Calvinist, yet he ruled a Lutheran people. He failed to turn the strategic position of Brandenburg to advantage in the Thirty Years War, and his possessions were devastated by the armies of both sides. After a long neutrality, he was in 1631 forced into a Swedish alliance by his brother-in-law, Gustavus II. After the Swedish defeat at Nördlingen (1634), he changed sides and, influenced by his powerful Catholic minister, Adam von Schwarzenberg, allied himself with the Holy Roman emperor (Treaty of Prague, 1635). The Swedes ravaged N Brandenburg. Discouraged by the invasions and misfortunes of his realm, George William retired to Königsberg (1638), leaving the state to Schwarzenberg's management. He was succeeded by his son, Frederick William (the Great Elector).