In 1639, however, he again overran northern Germany, defeated the Saxons at Chemnitz and invaded Bohemia itself. The winter of 1640–1641 Banér spent in the west. His last achievement was an audacious coup de main on the Danube. Breaking camp in mid-winter (a very rare event in the 17th century), he united with the French under the Comte de Guébriant and surprised Regensburg, where the Diet was sitting. Only the break-up of the ice prevented the capture of the place. Banér thereupon had to retreat to Halberstadt. Here, on 10 May 1641, he died, possibly due to advanced liver cirrhosis caused by his excessive alcohol consumption,Peter Englund, 'Ofredsår: Om den svenska stormakstiden och en man i dess mitt', Atlantis (1993) after designating Lennart Torstenson as his successor. He was much beloved by his men, who bore his body with them on the field of Wolfenbüttel. On the other hand, the enemies of Sweden rejoiced and a parody requiem hoping that he was burning in hell was even composed in Bohemia, which had been badly pillaged by Banér. He was buried at the Riddarholmen Church in Stockholm.Åstrand, Göran; Aunver, Kristjan (1999), 'Här vilar berömda svenskar: uppslagsbok och guide'. Bromma: Ordalaget. p. 20.
In 1639, however, he again overran northern Germany, defeated the Saxons at Chemnitz and invaded Bohemia itself. The winter of 1640–1641 Banér spent in the west. His last achievement was an audacious coup de main on the Danube. Breaking camp in mid-winter (a very rare event in the 17th century), he united with the French under the Comte de Guébriant and surprised Regensburg, where the Diet was sitting. Only the break-up of the ice prevented the capture of the place. Banér thereupon had to retreat to Halberstadt. Here, on 10 May 1641, he died, possibly due to advanced liver cirrhosis caused by his excessive alcohol consumption,Peter Englund, 'Ofredsår: Om den svenska stormakstiden och en man i dess mitt', Atlantis (1993) after designating Lennart Torstenson as his successor. He was much beloved by his men, who bore his body with them on the field of Wolfenbüttel. On the other hand, the enemies of Sweden rejoiced and a parody requiem hoping that he was burning in hell was even composed in Bohemia, which had been badly pillaged by Banér. He was buried at the Riddarholmen Church in Stockholm.Åstrand, Göran; Aunver, Kristjan (1999), 'Här vilar berömda svenskar: uppslagsbok och guide'. Bromma: Ordalaget. p. 20.