When Muslims had almost reached Aleppo in 635, Heraclius and Yazdegerd (III) sought an alliance and Heraclius married off his [grand?] daughter to Yazdegerd and they both were set to mount a simultaneous attack on Muslims: Heraclius from Northern Syria and Yazdegerd from Iraq simultaneously.

But why couldn't it happen and instead we saw no offensive from Yazdegerd on east while all the Muslim army (and especially all the notable commanders including Khalid ibn Walid were in Syria) and continued their progression (all the way till epic battle of Yarmouk)

So question is simple: Why couldn't Yazdegerd coordinate with his father-in-law to crush their common (and most loathed due to monotheism) enemy?

  • 1
    Can you show a source for the marriage of Yazdegerd(III) to a descendant of Heraclius?
    – justCal
    Apr 13, 2017 at 5:24
  • 2
    Christianity and Zoroastrianism are both considered monotheistic as well. Whatever the problems the three parties had with each other were, monotheism wasn't one of them.
    – T.E.D.
    Apr 13, 2017 at 14:16
  • 2
    @T.E.D. Muslims generally criticize Christians as being only monotheists in name, but not practice. The doctrine of the Trinity and veneration of saints, both of which were already widespread in the 7th century, appears much more polytheistic than monotheistic to outsiders. I can't say much about Zoroastrianism.
    – user1973
    Apr 13, 2017 at 20:01
  • 2
    @fredsbend - Perhaps, but I'm not real interested in chasing after a "No True Scottman" argument in this forum. Fighting out the definitional meanings I'll leave to folks who specialize in such things, like Wikipedia, who currently term all 3 religions "monotheistic".
    – T.E.D.
    Apr 13, 2017 at 20:12
  • 2
    @T.E.D. I'm not trying to lay down definitions. I'm trying to give context that "monotheism" could very well be the problem muslims at that time had with christians.
    – user1973
    Apr 13, 2017 at 21:30

1 Answer 1


The wikipedia page of Battle of Yarmouk you cite, had impressions on this.

Vahan was instructed by Heraclius not to engage in battle until all avenues of diplomacy had been explored.[58] This was probably because Yazdegerd III's forces were not yet ready for the offensive in Iraq. Accordingly, Vahan sent Gregory and then Jabalah to negotiate, though their efforts proved futile. Before the battle, on Vahan's invitation, Khalid came to negotiate peace, to a similar end. These negotiations delayed the battles for a month.[38] On the other hand, Caliph Umar, whose forces at Qadisiyah were threatened with confronting the Sassanid armies, ordered Sa`d ibn Abi Waqqas to enter into negotiations with the Persians and send emissaries to Yazdegerd III and his commander Rostam Farrokhzād, apparently inviting them to Islam. This was most probably the delaying tactic employed by Umar on the Persian front.[59] Meanwhile, he sent reinforcements[38] of 6,000 troops, mostly from Yemen, to Khalid. This force included 1,000 Sahaba (companions of Muhammad), among whom were 100 veterans of the Battle of Badr, the first battle in Islamic history, and included citizens of the highest rank, such as Zubayr ibn al-Awwam, Abu Sufyan, and his wife Hind bint Utbah.[60]

It is said( by I do not remember who), the byzantines were supposed to wait for the arrival and uniting with the sassanids. On the battlefield of Yarmouk, they waited for a month. Umar sent a constant stream of reinforcements, which gave Vahan the impression that the muslim armies were really large, and that waiting for battle anymore would turn the odds against them. On the front with the persians, there were the stalling moves, of negotiating and inviting to islam , which kept them occupied and unable to co-ordinate.

Pardon the vagueness.

  • 3
    This is a good illustration of the fusion between politics and war, and how time is a factor in battle. Nicely put. Jun 14, 2017 at 12:48

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.