For Heraclius, 626 was a year of little action — it appears that in an attempt to bolster his forces, he promised the hand of his daughter Epiphania to the Khan of the Western Turkic Khaganate, Ziebel.
Impressed by the offer, the Khan fielded some 40,000 troops on the Byzantine side.
However, the Khan died just two years later, in 628.
Nonetheless, Byzantium made good use of the boost in troops when Heraclius marched into Mesopotamia the following year.
His objective was clear: to destroy the Persians' army and march to Ctesiphon, doing what no Roman Emperor had done in nearly three-hundred years (since the days of Julian the Apostate): .
His army marched cautiously into this hostile terrain.
It was known to Heraclius that a Persian force was close and an ambush was always a possibility.
Meanwhile, Rhahzadh, the new Persian commander, was also not keen to face Heraclius until his army was ready for a pitched battle.

After spending a greater part of 627 in Mesopotamia, Heraclius finally encountered the Persian army close to the ruins of the city of Ninevah.
For eleven hours, the Byzantines and the Persians fought each other continuously.
In the thick of the fighting Razates issued a challenge to Heraclius, who accepted.
Despite being wounded, Heraclius managed to decapitate Razates.
When the sun finally began to set, the Persians had been defeated and both armies rested.

Heraclius later moved on to the Great Palace of Dastagird only to discover that Khosrau II had fled his Palace.
In a fit of rage, Heraclius ordered that everything be burnt to the ground.
Moving on, he soon found that Khosrau no longer commanded the loyalty of his subjects — as they refused to rally to defend Ctesiphon.
Heraclius waited a week or two before marching his army back.
Khosrau's son Siroes took power as Kavadh II and had his father shot to death with arrows.
Later, the formation of a peace treaty favourable to the Byzantines led to the restoration of the pre-war boundaries.
As an added bonus, all captives and Christian relics that had been captured by the Persians were returned.
Thus, it was at the head of the True Cross that Heraclius entered the Capital on September 14, 628 triumphant.
Leading a procession which included four elephants, the True Cross was placed high atop the altar of the Hagia Sophia.

By this time, it was generally expected by the Byzantine populace that the Emperor would lead Byzantium into a new age of glory.
However, all of Heraclius' achievements would come to naught, when, in 633, the Byzantine-Arab Wars began.
For Heraclius, 626 was a year of little action — it appears that in an attempt to bolster his forces, he promised the hand of his daughter Epiphania to the Khan of the Western Turkic Khaganate, Ziebel. Impressed by the offer, the Khan fielded some 40,000 troops on the Byzantine side. However, the Khan died just two years later, in 628. Nonetheless, Byzantium made good use of the boost in troops when Heraclius marched into Mesopotamia the following year. His objective was clear: to destroy the Persians' army and march to Ctesiphon, doing what no Roman Emperor had done in nearly three-hundred years (since the days of Julian the Apostate): . His army marched cautiously into this hostile terrain. It was known to Heraclius that a Persian force was close and an ambush was always a possibility. Meanwhile, Rhahzadh, the new Persian commander, was also not keen to face Heraclius until his army was ready for a pitched battle.
After spending a greater part of 627 in Mesopotamia, Heraclius finally encountered the Persian army close to the ruins of the city of Ninevah. For eleven hours, the Byzantines and the Persians fought each other continuously. In the thick of the fighting Razates issued a challenge to Heraclius, who accepted. Despite being wounded, Heraclius managed to decapitate Razates. When the sun finally began to set, the Persians had been defeated and both armies rested.
Heraclius later moved on to the Great Palace of Dastagird only to discover that Khosrau II had fled his Palace. In a fit of rage, Heraclius ordered that everything be burnt to the ground. Moving on, he soon found that Khosrau no longer commanded the loyalty of his subjects — as they refused to rally to defend Ctesiphon. Heraclius waited a week or two before marching his army back. Khosrau's son Siroes took power as Kavadh II and had his father shot to death with arrows. Later, the formation of a peace treaty favourable to the Byzantines led to the restoration of the pre-war boundaries. As an added bonus, all captives and Christian relics that had been captured by the Persians were returned. Thus, it was at the head of the True Cross that Heraclius entered the Capital on September 14, 628 triumphant. Leading a procession which included four elephants, the True Cross was placed high atop the altar of the Hagia Sophia.
By this time, it was generally expected by the Byzantine populace that the Emperor would lead Byzantium into a new age of glory. However, all of Heraclius' achievements would come to naught, when, in 633, the Byzantine-Arab Wars began.
Byzantine Empire under the Heraclian dynasty