My dissertation examines radical Protestant propaganda of the Thirty Years’ War (1618-1648). It investigates the radicals’ depiction of foreign allies of the German Protestants as well as the presentation of German Catholic leaders in pamphlets and broadsheets of the war. Through analysis of representative sources portraying Prince Bethlen Gabor of Transylvania and King Gustavus Adolphus of Sweden, it examines the arguments used to gain support for foreign Protestant figureheads among the moderates of the Protestant camp. The dissertation also investigates the presentation of Emperor Ferdinand II and Duke Maximilian of Bavaria in order to determine how propagandists denounced German Catholic rulers as no longer worthy of German Protestant allegiance or tolerance. My conclusion demonstrates how radical propagandists sought to change moderate Protestant attitudes towards German Catholic rulers and foreign allies through a cohesive and sophisticated campaign.