In 1420, Eric V attacked Prince-Elector Frederick I of Brandenburg and Lübeck allied with Hamburg in support of Brandenburg. Armies of both cities opened a second front and conquered Bergedorf, Riepenburg castle and the Esslingen river toll station (today's Zollenspieker Ferry) within weeks. This forced Eric V to agree with Hamburg's burgomaster Hein Hoyer and Burgomaster Jordan Pleskow of Lübeck to the Peace of Perleberg on 23 August 1420, which stipulated that all the pawned areas, which Eric IV, Eric V and John IV had violently taken in 1401, were to be irrevocably ceded to the cities of Hamburg and Lübeck.