Romans start using the saddle and Eucherius becomes British Emperor?
nope
Chapter XVIII: Constantinopolis
“Aetius: the greatest general our time has seen.” – Arcadius
Philippus was torn between joy and grief as he saw that the Roman army was fleeing. Sirmium was now without defence. The city fell and Philippus saw how the Roman civilisation began to burn down. In the last decades Sirmium saw many invaders, but none of them, not Goths, Gepids or Sciri, harmed the city as much as the Huns. For Ultzindur Sirmium was a symbol, the Romans, especially Arcadius and his clan, should fear him. The Hun himself led the most of his men to the south-east, some supported Asterius’ troops in the west, only a few stayed behind in Pannonia and Dacia. The heartland of the east, Thracia, is Ultzindur’s destination. The city of Constantinus must fall if he wants to succeed.
During the spring and the summer of 430 the Huns devastate the Illyricum, whereas Asterius operates in the Rhodanian valley against Eucherius troops. Britannian Lusitania fell already to the western troops but Galicia not, the mountains protect the last bulwark of Eucherius and Constantinus IV. on the peninsula.
The late summer sees the fall of Thessalonica and the birth of Eucherius first grandchild, Flavia Maria. The foederati that were once settled in Dalmatia, namely Sciri, Eruli, alani and the rests of the Gepids, refuse to follow Arcadius in the war. Instead they ally with Asterius and Ultzindur to avoid their own destruction. Constantinopolis’ last hope is Aetius, the mightiest general of the east and son-in-law of the emperor. Aetius arrives in the capital at the 27th September of 430, exactly one month later his troops stand not far away from the city, face to face with the Huns. History will remember the name of this battle, Aetius will be immortal, some will call him the last Roman, the man who faced the Huns and led his men in the battle, some will compare him to Stilicho, both gave everything, both were always loyal and both share the same destiny. They died on the battle field; Stilicho at Narona, Aetius at Heraclea.
Unlike Stilicho, Aetius offspring never will come to glory; the outraged population of Constantinopolis lynched his family, before the Huns even begun to siege the city. The rest of the imperial family had to flee to the east. Ultzindur sat his friend and advisor Philippus on the throne of the east. Many people died in the days of the sack of Constantinopolis. The patriarch himself was slaughtered by the Huns. Aetius couldn’t save the city, no one could. The Theodosian dynasty lost all its land in Europe and went to Alexandria, where Arcadius died in the summer of 431. Theodosius didn’t appoint a successor for his uncle, in his eyes he was now ruling east and west alone – actually with Constantinus together but Britannia is far away. The Huns in the meantime went to conquer Asia. They would have probably been in Antiochia at the end of the summer but Asterius needed more troops in the west. The city of Rome rebelled, no grain from the Vandals, which were allied to the Theodosians, meant no food, the population was starving again. A man named Balbianus became emperor, for two weeks before they killed him. After that some Licinus; he also didn’t stay on the throne for long.
The autumn of 431 sees the fall of Rome, the Huns restore Aurelianus to the throne. Gallia is in chaos; Eucherius could not finish his campaign against the Germans at the Rhenus and has now also to deal with the Goths. The turning point of the war comes in Gallia with the death of Himivin, the first king of all Goths. He fell in the battle against Eucherius troops, not the enemy’s swords and spears killed him but the cowardice and weakness of the Romans. The left flank collapsed, mostly Roman and Hunnic cavalry, Himivin wanted to stop them from fleeing the field but his horse reared up and the king fell, killed by the hooves of his own troops. The battle ended with the defeat of the Goths and with a new king, Theodavin, son of Himivin. Legates are sent, to the rulers all over the Roman world, making and breaking alliances. He offers the hand of one of his sisters to Aelius Gratianus, son of Arcadius and candidate for the throne of the east - should the Theodisians ever return to Constantinopolis - and the king also suggests marriage between his daughter and Geiseric’s son. Both agree.
In Alexandria the imperial family lives less luxurious than in Mediolanum or Constantinopolis but at least they live safe. The patriarch of the city, Cyrillus, showed to be a friend of the dynasty and also Eparchius Avitus, a man who built up a good reputation as general in the war against Persia, supports their claims. Latter will lead the remains of the imperial army to the north. Constantinopolis will fall later or sooner, to one faction or the other, two years are not enough, this war has just begun.