the lack of mention of Anthemius however is more a proof of his weak contribution to the expedition rather than a proof of his extraneity.
Procopius is quite clear, tough, about where the motivation of the campaign is, which is in Constantinople and not in Ravenna, Anthemius litterally being said to have been chosen as colleague because Constantinople needed help to take back Africa. Is it a definitive proof? No, I agree.
But it's a mention with a great interest when it's added to a quick overview of Constantinople and Ravenna's capacities : the incapacity of WRE to pull anything at this point plus the mention of Anthemius as a junior partner even in this campaign...It's not anecdotical.
And, eventually, the lack of sources or mentions (as far as I could find, but I'd welcome any one that I would have missed) that would support the idea Ravenna was to "inherit" Africa makes this very idea unsubstantiated and made out of habit more than anything. It's not impossible: after all Leo did used the claim of Ravenna's dominance over Vandals as a casus belli and would have likely given Anthemius some sort of dominance over the region.
Beside an African campaign, in my opinion, would require a certain degree of logistical support from any power based in Italy. This maybe doesn’t prove anything about the destiny of Africa but maybe the wre involvement was not so insignificant.
If we go by our main contemporary primary sources there, we have few mention of Anthemius or WRE's participation. Which, of course, doesn't mean he didn't participated but the essential part of the logistic was provided by Constantinople. We're talking more than one thousand ships (when Majorian was credited with a large fleet by gathering 300), three main armies whom two were lead by Eastern Romans and one by Marcellinus,
In fact, the only mention made of Anthemius on this regard was (from Candidus) that "adequate ammounts [were] raised from the public funds and from the Emperor Anthemius" which is not really much in comparison of the claimed 64,000 pounds of gold and the 700, 000 pounds of silver gathered by Leo for the expedition. It's more or less the late ancient equivalent of "I'm helping!".
Most of the expected geologistical support was to come from an Sicily retaken by Marcellinus : don't get me wrong, I've no doubt that military forces were sent by Anthemius even if they're not directly mentioned. But clearly not under WRE's direction.
However I want to discuss this from another perspective: the Roman were used to the idea of multiple emperors,probably they also recognized the need occasionally.
Of course, but it turned quickly to be a non-territorial collegiality rather than a return to West/East division that lost virtually all relevance both politically and strategically in the late Vth onwards. You mention the tentatives of reestablishment of western imperium, but AFAIR, these were rather usurpations that began in the West and attempted at topple who ruled in Constantinople, rather than restauring WRE, like Heraclius did.
By keeping Africa for himself, Leo basically undermine Anthemius’position (his man) and the whole idea of sending someone trustworthy (albeit subordinate) to the western provinces.
Leo was working on a thin line in WRE, admittedly. He sent Anthemius because Ravenne's court was a joke and at the very least needed some imperial dignity and legitimacy. But he was (as Anthemius) stuck between a Barbaro-Roman more or less led by Ricimer (and with an overriding and decisional power comparable to Aspar's in Constantinople) and an Italo-Roman factions whom each hated the guts out of the other, but found themselves together in a common defiance of Anthemius. Giving the history of Ravenne's policies, and while he would certainly have given Anthemius more than a token rule over Africa, it's really likely that a man as Basiliscus (which was really high-ranked and close to power) would take the direct rule of the region and would answer more to Constantinople than to Ravenna for the simple reason the latter didn't (couldn't) lead the expedition and couldn't control the territory.
Eventually, I don't even think it would be a that conscious policy from Leo to limit Anthemius' influence in Africa, but just a consequences of the geopolitical realities unfolding more or less by themselves.
The questions here is would the addition of Africa and later Italy (with the connected risk of usurper and separatist coming from the West) be more beneficial to the ere than a loyal and stable wre whose emperor has been sent there for exactly this purpose?
You forget there than WRE was an imperial hotseat, where the average reign was incredibily short. WRE wasn't stable in any sense of the world, and the necessity of Constantinople to regularily pull a candidate out of its sleeves and being forced to support him with their own resources for a net result being dangerously close to "lol, no".IOTL they went with the disappearance of WRE and the support of patricianship because it was too much hassle for a token Italy.
ITTL, however, Africa is in the basket and it's highly dubious they'd let emperors wanabees relaced every two seconds (and, more importantly, their Barbarian commander-in-chief) having a say in what was not only the most wealthy province of the region but also an important strategic plate (the expedition was decided after Vandals decided it would be a good idea raiding Greece). There was simply too much at stake to graciously abandon Africa to emperors that could not even survive on its own.
(assuming that Rome instead of Constantinople benefit from the reconquest,otherwise there wouldn t be many changes)
I think you're using the right words there : it's assuming they would do so, when frankly sources does point that Ravenne wasn't particularily concerned by the whole thing compared to Constantinople. I don't expect Leo to say "it's mine now, get lost" and Anthemius would probably get some acknowledgement of his imperial dominance with some financial gain, but would it be only the need to compensate for the really important sums involved in the campaign would limit these gains.
As for the lack of changes, I wholly disagree : I tried to point how an earlier and saner ERE advance in Central Romania, instead of a JUSTINIAN SMASH attitude would bring significant developments.
Speaking about the foreignness of Anthemius how would leo be better? He is equally an eastern but more distant and probably unable to keep Italy under constant control.
I didn't said it would happen overnight, I said WRE had basically the choice at this point being swallowed up by Babarians as IOTL, or by ERE giving it was far too dependent from one or the other to stand on its own feet anymore.
Finally about the vandals, let’s follow your point: an eastern Roman ruled Africa means no need to rely so heavily on foederati for the defence of the province ( the eastern army is still facing the problem of barbarians inside the army but they should be making progresses) so why keeping them alive?
Of course they would be still in need of an army in Africa (the region already proved it was not protected by some plot armor). Would it be only because of the Berber raidings, and the very possible Gothic interest on this area (after Vandals, Goths had the only worth of mention navy in western Med), and even if nobody goes into Africa because reasons, nothing would have been won in the west just replacing Vandal piracy with Gothic piracy.
And as for the rest of western Romania, how can Ravenne not being dependent on foederati when they are litterally the only army they can dispose of, even if irregularily and not really trustworthy? Anthemius have simply no forces of its own.
I am not suggesting a genocide of the vandals but something similar to what happened after the vandalic war: the end of an indipendente vandal kingdom, with the survivors forced to join the army or relocated on the other side of the empire
There's an important difference : Vandals in the late Vth are at the apogee of their dominance in Africa, when Vandals in the mid-VIth were severely beaten by Berbers; with the development of Justinian's policies utterly rejecting the concept of foedi in fact (which backfired and how!). Pulling an inedite (because it would be inedite) decision like this, and that would cost yet other resources, would be frankly inane.
Even the claims made in the VIth they relocate the whole of Vandal population isn't really entierely credible, to be honest, and it would be even less ITTL.
Relocating them would be difficult but why do you need to rely on the same warriors that recently threatened the survival of your empire?
Because there wasn't much other credible alternative : you still forgetting that each time, and litterally so, that a foedus was reduced into obedience in western Romania so far, it was kept in the same rough region. That is a basic fact of late imperial geopolitics : they depended too much on Barbarians against other Barbarians to just make them disappear.
I want to finally note that the vandal settlement in Africa didn t reply to any particular Roman need (basically the Romans didn t asks them to move to Africa to protect the province, before being betrayed) but to particular conditions: a civil war.
Literally no one claimed this.
Anyway, the point isn't that everything Barbarians did was piloted by the imperial court or pretenders. It was rather that, while largely autonomous polities with a decisive nuisance power that, historically, led to the collapse of the Roman state in the west, Romans couldn't just get rid of them even (and critically) in this situation because to fight them, they essentially had to use other foedi and that since the 430's. The military dependence on effectively independent (if integrated) bodies was far too important : the only way to counter that was to be dependent on the Eastern Roman resources.
