From the Upper Palatinate, he passed into the Rhenish Palatinate. Here he relieved Frankenthal and took Hagenau; then, joined by his master, the elector Frederick, he defeated Tilly at Wiesloch (25 April 1622) and plundered Alsace and Hesse. However, Mansfeld's ravages were not confined to the lands of his enemies; they were ruinous to the districts he was commissioned to defend. At length Frederick dismissed Mansfeld's troops from his service. With Christian of Brunswick the count then entered the service of the United Provinces and marched to the Republic through the Spanish Netherlands. In August 1622, at Fleurus his army had to fight its way through a Spanish attempt to block him. His army recuperated and reequipped in September and then marched with the Dutch army to relieve the city of Bergen op Zoom, besieged by Spain. After that, he took up his quarters in East Frisia, capturing fortresses and inflicting great hardships upon the inhabitants. A mercenary and a leader of mercenaries, Mansfeld often interrupted his campaigns by journeys made for the purpose of raising money, or in other words of selling his services to the highest bidder, and in these diplomatic matters he showed considerable skill.