Honestly, if you have a successful/surviving Soissons as the 'WRE' in practice, I'm not sure the ERE will allow them to have Italy, as in, they'd move in first if they could. Soissons would probably do better to secure Gaul, establish someone as a British Client, and then move on Spain, and create buffer states in Germania. Trading with the ERE is grand, and having the Goths in Italy has its benefits - the ERE won't be able to try and unite the Empire (which is a war the ERE is more likely to win than Soissons), until the Goths are dealt with, and if the Goths even slightly acknowledge Soissons as an overlord, it gives them Italy on paper and an ally on that border.
I think that the ERE might still take North Africa, because it did IOTL even with the Goths, but I harbour no belief that Soissons will be anything but a subservient state by the perspective of the ERE. They might call them Ruler of Gaul, Spain, etc - but not the equal of the ERE.
Assuming that this DOESN'T butterfly away the Caliphate (forgive me, but I don't see how Soissons would other than butterflies change everything), then you could see them offer to assist in exchange for recognition as equals, together I think they'd be more than able to reclaim any Caliphate-style war losses
Besides that, it lives to push east through Germania, unless it decides that fighting the ERE is a worthwhile endeavour.
Long run? With the ERE and Soissons working together, I could see Soissons/WRE eventually centring itself around OTL Netherlands, leaving North Africa to the ERE - and competing with the ERE economically by going west so as to circumvent Eastern traders.
As to how, my first instinct is to set up in Paris - it is a better position. In addition, I'd try to bring in Saxons to settle the region and fight as soldiers - whilst reorganising Gallo-Romans around Paris, even if it means uprooting those in the now-Saxon territories. Choose an ally in Britain, someone to be a consistent trade partner, and stick with them. Take any children under a certain age from those defeated, and raise them as Romans - and leave their parents in the fields. Soissons literally has only got the options of inviting in more people to defend them, and/or making the Other into Romans.
Not my strong suit this bit of Roman history, but my understanding has been that the Romans there were strapped for cash, for manpower, for basically everything. Go where the money is, bring the people, and get them under control.
I think that the ERE might still take North Africa, because it did IOTL even with the Goths, but I harbour no belief that Soissons will be anything but a subservient state by the perspective of the ERE. They might call them Ruler of Gaul, Spain, etc - but not the equal of the ERE.
Assuming that this DOESN'T butterfly away the Caliphate (forgive me, but I don't see how Soissons would other than butterflies change everything), then you could see them offer to assist in exchange for recognition as equals, together I think they'd be more than able to reclaim any Caliphate-style war losses
Besides that, it lives to push east through Germania, unless it decides that fighting the ERE is a worthwhile endeavour.
Long run? With the ERE and Soissons working together, I could see Soissons/WRE eventually centring itself around OTL Netherlands, leaving North Africa to the ERE - and competing with the ERE economically by going west so as to circumvent Eastern traders.
As to how, my first instinct is to set up in Paris - it is a better position. In addition, I'd try to bring in Saxons to settle the region and fight as soldiers - whilst reorganising Gallo-Romans around Paris, even if it means uprooting those in the now-Saxon territories. Choose an ally in Britain, someone to be a consistent trade partner, and stick with them. Take any children under a certain age from those defeated, and raise them as Romans - and leave their parents in the fields. Soissons literally has only got the options of inviting in more people to defend them, and/or making the Other into Romans.
Not my strong suit this bit of Roman history, but my understanding has been that the Romans there were strapped for cash, for manpower, for basically everything. Go where the money is, bring the people, and get them under control.