An army of 600 cavalry and additional infantry led by Count Gottfried of Leiningen (a younger relative of the cathedral dean of the same name), attacked northern Hesse from Fritzlar, an exclave of Mainz, and devastated the area around Gudensberg, Felsberg and Melsungen. However, they were defeated by Landgrave Louis I in a battle between the village of Großenenglis and nearby Holzheim (now an abandoned village), a few kilometers south of Fritzlar. Louis I defeated Gottfried again in pursuit engagements at Jesberg, Felsberg, and Fritzlar. Gottfried retreated to Fulda, where Conrad was ready with a second army. However, the city and monastery of Fulda refused Gottfried the protection of their city walls, and his army was decisively defeated on August 10. On 8 December 1427, a peace treaty between Hesse and Mainz was signed in Frankfurt. Mainz had to accept almost all of its possession in Upper and Lower Hesse as Hessian fiefs, only Fritzlar, Naumburg, Amöneburg and Neustadt remained as allodial Mainzer possessions in the area. This spelled the end of Mainz's territorial aspirations in northern Hesse. Only a few years later, there were violent clashes between the patricians and the guilds in Mainz. There were also tensions between the citizens and the clergy. In 1430, the patricians angrily left the city. In 1432, the city attempted to tax the clergy, and they left the city in 1433. Conrad excommunicated the city on 14 May 1434. However, Conrad died a few weeks later. He was buried in Mainz Cathedral on 10 June 1434. His grave monument was probably sculpted by Madern Gerthener, whom Conrad knew from his period as pastor as St. Bartholomew. Gerthener had also sculpted the grave monument of Conrad predecessor, John II of Nassau.