John Banér was the man who re-established the success of the Swedish arms. He resembled Gustavus Adolphus in greatness of mind and ability in war, paying back the execution of his father under Charles IX., by loyalty to the illustrious son of the latter. Banér was a typical soldier of the Thirty Years’ War, amiable, but licentious, and cruel to his enemies. An able tactician and strategist of inexhaustible resources, he had distinguished himself in the Polish war and later held many important commands. The death of Gustavus Adolphus stirred this strong man to the very depths of his soul. He left his army in Bavaria and arrived at Wolgast, resolved to leave the army. At the sight of the body of his beloved king, he was overcome by a paroxysm of grief. Axel Oxenstierna persuaded him to resume his command in order to bring the work of their dead master to completion. He marched with his army through Silesia to Bohemia, encamping before Prague. After the battle of Nœrdlingen he retreated to Saxony, whose deceitful elector he reproached with harsh words. Intrigues by the latter to bring the German troops in Swedish service to mutiny were frustrated by Banér, who had only 2,000 Swedes and Livonians with him. The Saxon army followed Banér into Mecklenburg, but suffered a defeat at Dœmitz. Banér marched eastward and joined the Swedish force, which met him, from Prussia, commanded by Lennart Torstensson. The elector of Brandenburg also declared war on Sweden, Banér answering by invading his country. From the vicinity of Berlin, Banér continued his way through Saxony back to Mecklenburg, his German troops marauding with such cruelty that they were sharply remonstrated with by Banér, who said he found it strange that God did not instantly punish them.
Banér was followed by the united armies of Austria and Saxony, but, having received reinforcements of Swedish troops, he turned on his tracks and met the enemy at Wittstock, in Brandenburg, September 24, 1636. The Swedish army consisted of 20,000 men, while the opposing force was much larger and occupied a favorable position on a hill. Banér won a glorious victory, thanks to a skilfully executed manœuvre. It grew dark, and the right wing of the Swedes was leading an almost forlorn hope against the overwhelming forces, when their left wing, after a difficult roundabout move, attacked the enemy from behind. Of the hostile armies every man was killed except a detachment less than 1,000 strong. The baggage, artillery and banners were taken, even the table silver of the elector and the imperial generals falling into the hands of the Swedes, who by this victory had regained their supremacy on German soil.