Early 749
The Khazars took advantage of winter, and for the first time, the armies were led by the khagan, and he set out to raid the territories of the Romans, as he moved, The khan, knew the byzantine theme army was harassing him, so he planted a trap, he divided his forces of 33 000 into 3 armies, luring the new strategos of Chaldia and armies of Lazica to fight 11 000, Both armies met and here the Khazars charged and later retreated.
The Byzantines followed, and felled for the trap, the Khazar army soon stopped at the designated point, and charged again while the other khazars horse archers began to rain arrows as the khazars charged, by the end, they Killed about ¾ of the 12 000, after the winter, Constantine now moved against the khan, the 3 Khazar armies began avoiding Constantine’s army.
Constantine threatened the Khazar communications from the Khazar khaganate and the Iberian front, this forced the Khazar forces in Iberia to retreat from the front lines, and face the emperor in the mountains, What followed was a spectacular Move, Constantine, divided his army of 50 000, into 5, to fool the other 2 Khazar armies to not come to the aid of the third and then Constantine 12 000, and spread the word of the size of his small army to lure the Khazar armies to attack, this worked.
But the emperor was not going to become overconfident and sent many scouts to report about the movement of his enemy’s army. Constantine scout discovered a hidden khazar force in ambush and responding to this ambush Constantine used the trick of the feigning retreat during the battle, the khazars left their cover in the mountains to chase the Byzantines, whereupon another 12 000 waited, once the trap was set, the second roman army led by the prince of Iberia, chased the khazars, causing them to flee, in the fighting the Khazar broke the encirclement and fled, still more than half them were killed or capture, but the byzantine casualties were not light as 6000 died.
Late 749
After his victory, both Romans and barbarians avoided each other, with minor engagements. then the other 2 Khazar armies and the survivors of the third army united, by winter. Both armies lead by Emperor Constantine, and Khazar khagan, met near Nelkari, After a series of maneuvers, the Byzantine army, caught up with the khagan army, which was heading towards the north, little was known about the battle only that the khanga and The emperor countered each other’s strategies the Romans used many tactics, after hours of fighting, The battle ended in a nominal victory for the Byzantines, the Byzantines lost 15 000 men among them the strategos of Chaldea and the Khazars some 9 000, the khagan withdrew in good order later sources state that there was a discussion and while the Byzantines took the field the Khazars suffered more casualties.
Mid 750 AD
The Khazars continued to March and raid many cities, the main Khazar army moved to the south, while the smaller raided the east, by spring Constantine moved against them having wintered in Bagavan while some khazars reached as far as Dvin, and then the emperor began to chase the Khazar while retreated still the emperor caught up with the Khazar khagan near Yerazgavors, the Khazars charged and retreated, yet the emperor told his army not to move,seeing how they didn’t fell for the trick and they repeated, the khagan ordered the horse archers to the sides, and the heavy cavalry in the center, this worked and the roman army retreated, and soon stalemate came.
During the battle the khagan saw the emperor and he saw him as well, the Khazar khagan readjusted his flag lance, as Constantine prepared the sword of Heraclius, Constantine avoided moved to avoid the lance and he struck the face of the Khazar khagan, but due to the angle of attack and the force behind it, the cut was not deadly, and both men lost balance. Due to this, both men fell from their horses, both men were now on foot, and the khagan was bleeding heavily from the left cheek to his right eyebrow, the fight was hard for both men, the lance gave the khan the reach advantage, but the blood was getting into his eye.
While he fought his other commanders especially the 3 princes began to fight with such ferocity that later sources said that they were like a wall, during these openings Constantine tried to end the duel, but as time went on the Khazar khagan was losing his strength and having slower reactions, at the end the Constantine slew him, Constantine also captured the Khazar khagan flag, as the Khazar forces saw that the emperor had the khans flag, they began to route, moments later, the Khazar reinforcements arrived but saw how the army was already in a massive rout they also fled. As the Romans began to chase them, in the end, 14000 Khazars were killed, after this, the Khazar armies fled north, abandoning the attacks and raids on the empire, not everyone could celebrate as the brave prince Vardan II in the Khazar retreat was killed when he was struck by an arrow and thrown off his horse.
751 AD
The treaty of Tbilisi was signed, even though Constantine gained no new territory, the Khazar khaganate was weakened, and the war gave many new riches to the empire. And for 10 years the Khazar had to pay a yearly tribute, the victory also inspired a mosaic in the church of Yerazgavors with the 3 princes standing as Constantine rose the sword of Heraclius against the Khazar khagan, there was also a mosaic in Patrav about the fallen prince the battles also inspired many illustrations in later books.