The city flourished as a trade centre until the Thirty Years' War (1618–48), when this position was lost due to incessant warfare. During the dramatic advance of the Swedish army of Gustavus Adolphus into Germany, the city was garrisoned by Swedes, but it was retaken by Imperial Catholic League forces in 1631. During this campaign, it was widely reported that the Catholic forces killed many of the Swedish and Scottish soldiers while they were surrendering. Later, according to the Scottish soldier of fortune Robert Munro, 18th Baron of Foulis, when the Swedes themselves adopted a "no prisoners" policy, they would cut short any pleas for mercy with the cry of "New Brandenburg!". The city, therefore, played an unconscious role in the escalation of brutality of one of history's most brutal wars.