In North Germany the war against the Imperialists was continued by the Swedes under Banner. On October 4, 1636, the Imperialists were defeated at Wittstock (province of Brandenburg, district of East Priednitz), whereupon the Swedes in that very same year overran Saxony and Thuringia. In 1637, to be sure, they were thrown back into Pomerania by Gallas, but in 1638 they reappeared in Saxony, and in 1639 won a brilliant victory at Chemnitz. Thereupon Banner undertook a campaign into Bohemia, whence, in 1641, he was forced to retire. Shortly afterwards (May 10, 1641) he died in Halberstadt. These campaigns spread severe pestilences throughout the above-mentioned regions of North Germany, particularly the southern part of Brandenburg and the modern province of Saxony. The largest part of the Altmark resembled a ‘large lazaret’; in Wittstock itself there were 305 deaths in the year 1636, in Bismark 163, and in Salzwedel 193; in Werben a plague broke out after the soldiers had been quartered there and lasted well into the next year. In Stendal it began in June 1636, and carried away 1,992 persons in that year, as compared with an average annual mortality of 120–30; nor does the number include the peasants that had fled to the city, 3,000 of whom died. The pestilence spread over the entire vicinity and wiped out whole villages. In Tangermünde a pestilence broke out even before the battle of Wittstock; it was borne thither by Imperialists and Saxon artillerymen. In Gardelegen, where Banner had his head-quarters, 500 people in the parish of St. Nicholas, and 1,205 in the parish of St. Mary, succumbed in the year 1636 to bubonic plague and other diseases, among the dead being 195 soldiers. In Neuhaldensleben, whither many country-people had fled, a plague broke out in May 1636, and spread throughout the entire vicinity; in many days in September, thirty and more bodies were counted, while the incomplete church register records 778 deaths. The total number of deaths is said to have been 2,560.