What if Constantine made his eastern capital on the Asian side of the straits, long-term impact?

[raharris1973]

What if Constantine made his eastern capital on the Asian side of the straits rather than the European, in one of the historic cities of the region like Chalcedon, Nicomedia, or Nicaea, or a new city?

Just like in historic Constantinople, there are some decently fortifiable peninsulas, and the region is still near Black Sea grain shipping routes.

However, would capital being on the Asian side be a critical and possibly fatal vulnerability in some of the Empire's wars, for instance allowing the Sassanid Persians, or Arabs, or Seljuk Turks an opportunity to seize and hold the city and put the Eastern Roman Empire out of business permanently, earlier than OTL?

 

[WolfBear]

However, would capital being on the Asian side be a critical and possibly fatal vulnerability in some of the Empire's wars, for instance allowing the Sassanid Persians, or Arabs, or Seljuk Turks an opportunity to seize and hold the city and put the Eastern Roman Empire out of business permanently, earlier than OTL?

Very possibly, Yes. Of course, the butterflies from this would almost certainly mean no Islam in our TL's form, for one.

 

[Buba]

Chalcedon would be the mirror image of Constantinople.
Yup, the Sassanids would had besieged it in the early 600s. Would they take it? Maybe, possibly ... they were more technically savvy then the Avars, for sure
In which case i.e. Persian conquest - the capital is moved to Thessalonika.
Does this mean no Heraklian reconquista? It should still happen, but ...
If not - do the Sassanids (or offshots, as there could be rebelions in Syria or Egypt by then) beat off the Arabs?
Butterflies for teh win!!111

 

[raharris1973]

Yup, the Sassanids would had besieged it in the early 600s. Would they take it? Maybe, possibly ... they were more technically savvy then the Avars, for sure

interesting

In which case i.e. Persian conquest - the capital is moved to Thessalonika.

But under such circumstances, could Thessalonika be held from the Avars?

Does this mean no Heraklian reconquista? It should still happen, but ...
If not - do the Sassanids (or offshots, as there could be rebelions in Syria or Egypt by then) beat off the Arabs?

Assuming no Heraklian reconquista, the Sassanids could perhaps beat off the Arab challenge, or at least contain it, being in a stronger position relative to OTL. On the other hand, Sassanian conquest of the Asian and Egyptian Roman lands still would have been a major exertion, there wouldn't be too much time before the Arabs come, the Sassanids also had alot of internal weaknesses and succession problems and could be under pressure from Turks in the north too, so the Arabs could inherit their empire.

Ironically, in the first generation of Arab conquest, Roman remnants in Sicily, Africa, Crete could consider the Arabs allies against the common Persian foe.

But that's all presuming that butterflies don't do away with Arab unity and Islam.

 

[Buba]

But under such circumstances, could Thessalonika be held from the Avars?

Why not? Not that dissimilar - can be supplied by sea. Nothing changes the Avars not having a seagoing fleet.

But that's all presuming that butterflies don't do away with Arab unity and Islam.

By 615 Islam was in full swing already

https://en.wikipedia.org/wiki/Shahin%27s_invasion_of_Asia_Minor_(615)

 

[stevep]

Why not? Not that dissimilar - can be supplied by sea. Nothing changes the Avars not having a seagoing fleet.


By 615 Islam was in full swing already

https://en.wikipedia.org/wiki/Shahin%27s_invasion_of_Asia_Minor_(615)

By 615 Islam is starting but a change in ~310 could have immense butterflies. All those civil wars and other issues could mean that Islam is butterflied. Or the Phocas revolt for that matter which triggered the final round of Byzantine-Sassanid war.

One other possibility. With the capital on the Anatolian shore does it and related areas such as Syria at least be seen as more important than the Balkans and hence more emphasis on defending and developing them while the European territories suffer worse in the following centuries, possibly being devastated even worse by the Huns and others? You could have an eastern empire than largely gives up on much of the Balkans, as long as they control the straits, but is stronger in areas such as Armenia, northern Mesopotamia and the like? The Asian regions are much richer and also markedly more important religiously.