The Byzantines moved quickly to take advantage of their victory; a Byzantine army invaded Arab-held Armenia and, sometime in October or November, defeated and killed Emir Ali ibn Yahya.
In a single campaigning season, the Byzantines thus eliminated the three most dangerous opponents on their eastern border.
These successes were decisive, permanently destroying the power of Melitene.
The Byzantine victory at Lalakaon altered the strategic balance in the region and marked the beginning of Byzantium's century-long offensive in the East.

The importance of these victories did not go unnoticed at the time.
The Byzantines hailed them as revenge for the sack of Amorium 25 years earlier, the victorious generals were granted a triumphal entry into Constantinople, and special celebrations and services were held.
Petronas received the exalted court title of magistros, and the kleisoura of Charsianon was raised to the status of a full theme.
Al-Tabari reports that the news of the deaths of Umar and Ali—"strong defenders of Islam, men of great courage who elicited enormous praise among the frontier districts where they served"—provoked an outpouring of grief in Baghdad and other cities, culminating in riots and looting.
Although private donations and volunteers for the holy war began to gather at the border, "the central authorities [were not] prepared to send a military force against the Byzantines on their own account in those days" because of ongoing internal turmoil in the Abbasid Caliphate.

The removal of the eastern threat and increasing Byzantine confidence also opened up opportunities in the west, where the Bulgarian ruler Boris (r. 852–889) had been negotiating with the Pope and Louis the German (r. 817–876) for the conversion of himself and his people to Christianity.
The potential expansion of Rome's ecclesiastic influence to Constantinople's doorstep could not be tolerated by the Byzantine government.
The victorious eastern armies were transferred to Europe and invaded Bulgaria in 864, a demonstration of military might which convinced its ruler to accept Byzantine missionaries instead.
Boris was baptized—taking the name Michael in honor of the Byzantine emperor—beginning the Christianization of Bulgaria and his nation's absorption into the Byzantine-influenced Eastern Christian world.
The Byzantines moved quickly to take advantage of their victory; a Byzantine army invaded Arab-held Armenia and, sometime in October or November, defeated and killed Emir Ali ibn Yahya. In a single campaigning season, the Byzantines thus eliminated the three most dangerous opponents on their eastern border. These successes were decisive, permanently destroying the power of Melitene. The Byzantine victory at Lalakaon altered the strategic balance in the region and marked the beginning of Byzantium's century-long offensive in the East.
The importance of these victories did not go unnoticed at the time. The Byzantines hailed them as revenge for the sack of Amorium 25 years earlier, the victorious generals were granted a triumphal entry into Constantinople, and special celebrations and services were held. Petronas received the exalted court title of magistros, and the kleisoura of Charsianon was raised to the status of a full theme. Al-Tabari reports that the news of the deaths of Umar and Ali—"strong defenders of Islam, men of great courage who elicited enormous praise among the frontier districts where they served"—provoked an outpouring of grief in Baghdad and other cities, culminating in riots and looting. Although private donations and volunteers for the holy war began to gather at the border, "the central authorities [were not] prepared to send a military force against the Byzantines on their own account in those days" because of ongoing internal turmoil in the Abbasid Caliphate.
The removal of the eastern threat and increasing Byzantine confidence also opened up opportunities in the west, where the Bulgarian ruler Boris (r. 852–889) had been negotiating with the Pope and Louis the German (r. 817–876) for the conversion of himself and his people to Christianity. The potential expansion of Rome's ecclesiastic influence to Constantinople's doorstep could not be tolerated by the Byzantine government. The victorious eastern armies were transferred to Europe and invaded Bulgaria in 864, a demonstration of military might which convinced its ruler to accept Byzantine missionaries instead. Boris was baptized—taking the name Michael in honor of the Byzantine emperor—beginning the Christianization of Bulgaria and his nation's absorption into the Byzantine-influenced Eastern Christian world.
Battle of Lalakaon