He also recognized Matthias I of Hungary as his suzerain and received, in return, Ciceu and Cetatea de Baltă in Transylvania. The following year, however, he found himself alone when Mehmed II invaded Moldavia. The Moldavian army was defeated in the Battle of Valea Albă, but the Ottomans, suffering from a lack of provisions and an outbreak of the plague, were forced to retreat. Stephen the Great suffered the greatest setback of his reign in 1484 when the Ottomans captured Chilia and Cetatea Alba (now Bilhorod-Dnistrovskyi, Ukraine) on the Black Sea. Having tried unsuccessfully to regain the fortresses in 1485, he concluded a peace with the sultan and agreed to pay tribute to him.