In 1355 the Ottomans launched Process_start a campaign towards Sofia , but were soon engaged by the army of Ivan Alexander 's eldest son and heir Michael Asen close to Ihtiman .

Despite the victory and the death Death of young Michael Asen , the Turks were unable to reach Arriving Sofia .

He sent Sending Ivan Asen III , son of the former Emperor Mitso Asen , to claim Statement the Bulgarian throne at the head of a large Byzantine army .

He sent Sending Ivan Asen III , son of the former Emperor Mitso Asen , to claim Statement the Bulgarian throne at the head of a large Byzantine army .

In his absence the nobility in Tarnovo opened Openness the gates to Ivan Asen III .

However , Ivaylo broke Destroying the siege Besieging and Ivan Asen III fled Escaping back to the Byzantine Empire .

The Uprising of Asen and Peter ( ) was a revolt of Bulgarians and Vlachs living in Moesia and the Balkan Mountains , then the theme of Paristrion of the Byzantine Empire , caused Causation by a tax increase .

It began Process_start on 26 October 1185 , the feast day of St. Demetrius of Thessaloniki , and ended Process_end with the restoration of Bulgaria with the creation of the Second Bulgarian Empire , ruled by the Asen dynasty .

They sent Sending two leaders ( Peter and Asen ) to negotiate Communication with the emperor at Kypsella ( now İpsala ) in Thrace .

This was refused Agree_or_refuse_to_act , and Peter and Asen were treated roughly .

The brothers Peter and Asen built Building the Church of St Demetrius of Thessaloniki in Tarnovo , dedicated Giving to Saint Demetrius , who was traditionally considered a patron of the Byzantine city of Thessaloniki , and claimed Statement that the Saint had ceased Process_end to favour the Byzantines : `` God had decided Deciding to free Releasing the Bulgarians and the Vlach people and to lift Process_end the yoke that they had borne Bringing for so long '' .

The lands between the Haemus and the Danube were now lost Earnings_and_losses for the Byzantine Empire , leading to Causation the signing of a truce , thus de facto recognising Know the rule of the Asen and Peter over the territory , leading to Causation the creation of the Second Bulgarian Empire .

The Emperor 's only consolation was to hold Defending , as hostages , Asen 's wife and a certain John ( future Kaloyan of Bulgaria ) , brother of the two new leaders of the Bulgarian state .