Johan Banér (yōō´hän bänâr´), 1596–1641, Swedish field marshal in the Thirty Years War. He served (1626–29) in Poland and Russia and accompanied (1630) Gustavus II of Sweden to Germany. At Gustavus's death (1632) and the major Swedish defeat at Nördlingen, he became the chief Swedish general in Germany. Banér reestablished Sweden's military prestige at Wittstock (1636), where he defeated the Saxon and imperial forces. After recovering (1638) Pomerania and Mecklenburg and winning (1639) a victory over the Saxons at Chemnitz, he penetrated (1639) into Bohemia but was forced to retreat.