Currently the only way of doing it is by marrying into the other dynasty, supporting a pretender or otherwise taking the throne for yourself. In addition to that, if the other empire no longer exists you do get access to a decision allowing you to use Imperial Reconquest on the entirety of the area and thus to recreate the Roman Empire.

However, I don't think the precedent set by Constantine is valid in the mod period, and prefer it to be a challenge with pretenders and marriages, as it was historically between the WRE and ERE during this period, so I don't agree when it comes to adding a specific CB for this.

Perhaps if they turn away from Christianity you could sieze it. Or if they have negative prestige after ruling for X years or are a child.

Originally posted by SteveBeab:

Perhaps if they turn away from Christianity you could sieze it. Or if they have negative prestige after ruling for X years or are a child.

If they turn away from Christianity or have negative prestige it should be easy to install a pretender or encourage rebellions though.

It was Justinian who reconquered Carthage and Italy... The Mosaic on "The Gothic Win".

@Royal He isn't talking about Justininan, he was talking about Constantine. He went from being Caesar of a fourth of the Empire to being Imperator of all of it.

Also, it wasn't just Constantine that did it - Legati of legions siezing the throne of a section of the Empire was commonplace in Rome, and one Imperial ruler seizing the thrones of the other happened literally in every split before Theodosius's, and, more often than not, the person who comes out on top isn't a direct descendant of a past Emperor. If either empire managed to overcome the chaos and reform themselves to stop the Fall of Rome, that emperor would most likely claim the other empire.

In addition, there was no solid divide between the Eastern and Western emperors. The people of both empires belived themselves to be not West Roman or East Roman but just Roman. There was no real cultural divide between the two halves untill after Rome fell. The people would most likely accept one emperor seizing control of the entire Empire, and it would be easier to do so in this time period due to the instability of both empires. If one could stabilize, it could conquer the other.

I belive that there should be a CB for that, but it'd have to be pretty hard to use

*Primogeniture sucession (most likely still in place unless you had to reform either empire via decision as another country)
*High or max crown authority (You'd have to overcome the chaos of the period if you were to claim the other empire)
*2000 prestige cost (-500 discount if WRE or ERE or a dynasty that once ruled the RE)
*500 piety cost (-250 discount if WRE or ERE or a dynasty that once ruled the RE or target empire with one of the dynasty's emperors sharing the same religion of the person using the CB, if that's even possible)
*15 or more martial or Inspiring Leader
*One or more of the following traits: Brave, Ambitious, Proud, Quick, or Genius
*None of the following traits: Craven, Content, Humble, Maimed, Infirm, Incapable, Stupid, Imbecile, Dull, or Inbred
*Character rules an Empire-teir title and is Latin or Byzantine culture group OR rules a Kingdom-teir title and is Roman or Greek

It would be really hard to finally meet the criteria, but once you do then you can use the CB to conquer all titles held by a Latin-group or Byzantine-group kingdom or empire or the WRE or ERE (just in case the Isaurians stay or barbarians come to power). Adjust the requirements to your discretion.

@Danwar The references to Constantine and the divisions prior to Theodosius' death are not something which had a major impact on the way the empires interacted by 476. It was the choice of the ERE to not always intervene directly in the WRE affairs, although they did use their influence as we can see in the very beginning of the mod time frame. I think you have a far too catastrophic reading of the ERE though, which wasn't in a profound state of crisis until Justinian and the financial costs that ensued, with the 600s leading to almost annihilation.

There is nothing in the mod which prevents an emperor from conquering the other empire title, if they have have a claim or a pretender. But adding a largely circumstantial casus belli isn't necessary in my view, given that there is no real precedent and it wouldn't be particularly interesting for the player with too restrictive conditions.

Actually managed to do it. Married some guy who held a claim, he gave me a son, died, than I killed the emperor and put his daughter on the throne. After that, pressed the claim, my son came onto the throne, than I waited another 50 years before dying and finally inherited the eastern roman empire.

But than for some reason I couldn't reconquer ♥♥♥♥ anymore.

Pardon me for waiting so long to reply, just have been busy. Here we go.

Originally posted by Loup:

@Danwar The references to Constantine and the divisions prior to Theodosius' death are not something which had a major impact on the way the empires interacted by 476. It was the choice of the ERE to not always intervene directly in the WRE affairs, although they did use their influence as we can see in the very beginning of the mod time frame.

This is because the Eastern emperors (correctly) thought that attacking the West at the time would be fruitless seeing the state of decline the Western Empire was in, especially scince the WRE is basically doomed from the start in the 476 start and non-existent later.. However, if the West got back on its feet and began to show signs of healing, the Eastern emperors would be far more likely to view a conquest of the Western Empire favorably. A similar situation could be considered true: The West was too weak to try to reintegrate its eastern half, but if they recovered and began to take back their former territories, they might eventually have the power to take on a hopefully weakened Eastern empire.

TL;DR: The only reason neither side invaded the other was because of the impracticality of it. If either empire's ambitions shifted around a resurgent Western empire, an ambitious Emperor could seek to unify the Empire like many times before.

Originally posted by Loup:

I think you have a far too catastrophic reading of the ERE though, which wasn't in a profound state of crisis until Justinian and the financial costs that ensued, with the 600s leading to almost annihilation.

Thing is, in most of my games the Eastern empire collapses in on itself. Seriously, one game I think they even lost THRACE to an adventurer.

Originally posted by Loup:

@Danwar
There is nothing in the mod which prevents an emperor from conquering the other empire title, if they have have a claim or a pretender. But adding a largely circumstantial casus belli isn't necessary in my view, given that there is no real precedent and it wouldn't be particularly interesting for the player with too restrictive conditions.

Thing is, throughout Roman history there were plenty of times where people usurped the empire who DIDN'T have a ck2-style claim or pretender. They just decided to declare their Emperorship, prepare the Legion(s), and marched on Rome or wherever the capital of the Empire they were usurping was at the time.If you want a precedent for it, look at Octavian. Constantine. The Isaurians (which are actually represented in the game right now). Too many others to name. An ambitious ruler would be very much inclined to follow this trend.

Also, on the "too restrictive conditions", read the last sentence of my first post.
"Adjust the requirements at your discretion."

Originally posted by Danwar:

Pardon me for waiting so long to reply, just have been busy. Here we go.

No problems.

Originally posted by Danwar:

Originally posted by Loup:

@Danwar The references to Constantine and the divisions prior to Theodosius' death are not something which had a major impact on the way the empires interacted by 476. It was the choice of the ERE to not always intervene directly in the WRE affairs, although they did use their influence as we can see in the very beginning of the mod time frame.

This is because the Eastern emperors (correctly) thought that attacking the West at the time would be fruitless seeing the state of decline the Western Empire was in, especially scince the WRE is basically doomed from the start in the 476 start and non-existent later.. However, if the West got back on its feet and began to show signs of healing, the Eastern emperors would be far more likely to view a conquest of the Western Empire favorably. A similar situation could be considered true: The West was too weak to try to reintegrate its eastern half, but if they recovered and began to take back their former territories, they might eventually have the power to take on a hopefully weakened Eastern empire.

TL;DR: The only reason neither side invaded the other was because of the impracticality of it. If either empire's ambitions shifted around a resurgent Western empire, an ambitious Emperor could seek to unify the Empire like many times before

No, they would have tried to put in a pretender as they already did in the period before 476 with Anthemius, or invader after with Theoderic, Nepos and Odoacer all being in contact with the East. The ERE did intervene multiple times in this period though.

Originally posted by Danwar:

Thing is, in most of my games the Eastern empire collapses in on itself. Seriously, one game I think they even lost THRACE to an adventurer.

This is more a concern about balance than anything else.

Originally posted by Danwar:

Thing is, throughout Roman history there were plenty of times where people usurped the empire who DIDN'T have a ck2-style claim or pretender. They just decided to declare their Emperorship, prepare the Legion(s), and marched on Rome or wherever the capital of the Empire they were usurping was at the time.If you want a precedent for it, look at Octavian. Constantine. The Isaurians (which are actually represented in the game right now). Too many others to name. An ambitious ruler would be very much inclined to follow this trend.

You are confusing the usurpations with an outright conquest of the other half of the empire. The first was common in the period and will be implemented for each empire, but the latter didn't happen, since the East instead chose to send pretenders and invaders, which is represented in game.

Originally posted by Danwar:

Also, on the "too restrictive conditions", read the last sentence of my first post.
"Adjust the requirements at your discretion."

Yes, but when you start removing the requirements it gets too easy. Since there is no precedent for this mechanic in the time period, except with pretenders and invaders, this would be unbalanced no matter what.