Louis the German sent his armies against Moravia in 872. The imperial troops plundered the countryside, but could not take the "extremely well-fortified stronghold" where Svatopluk took refuge. The Moravian ruler even succeeded in mustering an army which defeated a number of imperial troops, forcing the Franks to withdraw from Moravia. Svatopluk soon initiated negotiations with Louis the German, which ended with a peace treaty concluded at Forchheim in May 874. According to the "Annals of Fulda", at Forchheim Svatopluk's envoy promised that Svatopluk "would remain faithful" to Louis the German "all the days of his life", and the Moravian ruler was also obliged to pay a yearly tribute to East Francia.