Banér had commenced the siege of Leipsic, when, upon news of an approaching army of the imperial allies, he was forced to undertake the famous “Retreat from Torgau,” which made him more celebrated than any of his great battles. He with his army was near being surrounded at the river Oder, but saved himself through a series of movements of the highest strategic skill. Cardinal Richelieu wrote that “this retreat, by means of which Banér saved 14,000 men, less a few fugitives and wounded, with cannon and baggage, against an army 60,000 strong, is to be compared to the most glorious deeds in history.” The enemy prided itself on having “caught Banér in a bag.” “Yes,” said Banér later, “surely they had me there, but they forgot to tie the string around.”
In Pomerania, Banér received the reinforcements from Sweden which he had awaited, and once more invaded Saxony, where he won a grand victory at Chemnitz, in 1639. The Swedish army invaded Bohemia, cruelly devastating the country. Banér made a daring attack upon Regensburg in order to make the emperor and the whole German diet his prisoners. Sudden thaws frustrated the plans, making it impossible for the Swedes to cross the Danube. A superior force was sent to meet Banér, who saved his army by another famous retreat back to Saxony. On the way Banér was attacked by a fever and died at Halberstadt, in 1641. When the imperialists learned of the death of the Swedish Leonidas, they thought they could easily defeat his army. The Swedes saw the approaching enemy and collected around the coffin of their dead hero, offering solemn pledges to fight for the glory of his name. They then made a sudden attack upon the imperial army, which suffered a thorough defeat at Wolfenbuttel. John Banér, triumphant in death like his great master, was buried in the Swedish Pantheon of the Riddarholm.
Banér had expressed the wish that Lennart Torstensson should succeed him as commander-general of the Swedish armies. Lennart Torstensson was a greater warrior even than John Banér; no Swedish general, Gustavus Adolphus not excepted, ever reaching higher skill or perfection in the science of war than this crippled hero. Torstensson was of a noble although not influential family. He entered the service of Gustavus Adolphus as a body page to the king, later distinguishing himself as an artillery commander. Torstensson took an honorable part in the battle of Breitenfeld, but made a prisoner at Nuremberg, he lost his health, during one year’s captivity, in a miserable dungeon. During his later brilliant career he suffered greatly from rheumatism, and was mostly carried around in a litter throughout the battles which covered his name with undying fame. He was a pious man of a gentle and cheerful disposition, who tried his utmost to reintroduce among his troops the excellent moral behavior and severe discipline which had been lost after the death of Gustavus Adolphus.