The Thirty Years' War (1618–48) prevented further development of the university. The Swedish kings wanted to destroy once and for all the bases from which the Catholic Church and the Jesuit Order drew the manpower and economic resources needed for their attempts to reintroduce the spiritual rule of Rome into the Scandinavian North. These were foremost the Jesuit College in Braunsberg, which fell into the Swedish hands in 1626, and Olomouc. The Swedes occupied Olomouc from 1642 to 1650. They plundered the university's vast library and the population of the town declined from over to . As a result, Olomouc University's most precious relics are now in the National Library of Sweden in Stockholm, including codices made under the patronage of Bishop of Olomouc Jindřich Zdík.