The Thirty Years' War reached Silesia when Protestant Ernst von Mansfeld started a military campaign against Hungary and crossed Silesia in 1629. This gave the emperor the chance to invade the country. The Silesian district authority became an imperial office. Albrecht von Wallenstein became lord of the Duchy of Sagan and of Glogau. The infamous "Liechtenstein dragoons" pressed the citizens of the principalities back into the Catholic Church or otherwise expelled them. Protestant landlords lost their possessions and were replaced by Catholic families.