Siege of Tarnovo The siege of Tarnovo occurred in the spring of 1393 and resulted in a decisive Ottoman victory . With the fall of its capital , the Bulgarian Empire was reduced down to a few fortresses along the Danube . Origins of the conflict . Tarnovo exceeded all Bulgarian towns by its size , its treasures , and its partly natural , partly artificial fortifications . Therefore , the Turks attacked this centre of Bulgaria first . The battle . In the spring of 1393 , Bayazid I gathered his troops from Asia Minor , crossed Helespont and joined with his western army ; probably that included some Christian rulers from Macedonia . He entrusted the main command to his son Celebi , and ordered him to depart for Tarnovo . Suddenly , the town was besieged from all sides . The Turks threatened the citizens with fire and death if they did not surrender . The population resisted but eventually surrendered after a three - month siege , following an attack from the direction of Tsarevets , on July 17 , 1393 . The Patriarch ' s church " Ascension of Christ " was turned into a mosque , the rest of the churches were also turned to mosques , baths , or stables . All palaces and churches of Trapezitsa were burned down and destroyed to the ground . The same fate expected the tzar palaces of Tsarevets ; however , parts of their walls and towers were left standing until 17th century . In the absence of Tsar Ivan Shishman , who attempted to fight the Turks elsewhere , leading the remnants of his troops to the fortress of Nikopol , the main Bulgarian leader in the town was Patriarch Evtimiy . He went to the Turkish camp with the intention of assuaging the Turkish commander , who listened politely to his pleas , but afterwards fulfilled very little of his promises . Celebi left the town after appointing a local commander . The new governor gathered all eminent citizens and boyars under a pretense and had them all killed . According to legend , Evtimiy was sentenced to death but saved at the last minute by a miracle . Aftermath . Later , the city ' s leading citizens were sent into exile in Asia Minor , where their historical traces are lost . The patriarch was sent into exile in Thrace . He died in exile and was later canonised as a national saint of his people . The citizens of Tarnovo that remained in the town saw what was described by contemporary sources as a " complete devastation of the town " . Turkish colonists occupied Tsarevets which from then on was called Hisar . The disciples of Evtimiy dispersed to Russia and Serbia , taking with them Bulgarian books , in the same way as the Greek learned men enriched the West with the old classics . Many merchants and boyars converted to Islam . The famous cathedral of the Holy Forty Martyrs , built by Ivan Asen II , somewhat damaged after the battle , was turned into mosque . The fall of Tarnovo and the exile of patriarch Evtimiy mark the destruction of the Bulgarian national church . As early as August 1394 , the Patriarch of Constantinople appointed the Moldovan metropolitan bishop to carry the episcopal trebes in Tarnovo , where he came the following year . In 1402 , Tarnovo had its own metropolitan , subjected to the Byzantine patriarch . Thus , the Bulgarian state fell under Turkish rule while the Bulgarian church fell under Greek rule .