One shouldn’t forget that Justinian (and his rather brilliant wife, Theodora) had planned to try and take Italy without unsheathing a sword (and that he tried it twice) by subverting the Ostrogothic kingdom at its head. And that despite some portrayals of Justinian as foolishly adventuring, he was quite willing to cut his losses at times in Italy and accept a partial conquest but was dissuaded by promises first from Belisarius then by other commanders that victory on the battlefield was attainable. Africa and the easy reconquest of Sicily plus disaffection among Romans in Italy and the Gothic royal family and its nobles all argued that Italy could be retaken with minimal cost. Justinian had rightly reasoned it pointless to take Italy without Africa to provide a steady grain supply as in the old days of the Western and United Empires and had wisely gambled on crushing the Vandal kingdom first. Now just as he had fished in Vandal political waters hoping the king Hilderic would either hand over the kingdom or more likely provide (as his murder did) a casus belli for invasion, he had hoped to undermine the Ostrogoth kingdom by playing the various Gothic factions against each other and adding into the mix, Theodora as provocateur. For as he reassured the tragic, doomed Queen Amalasuntha of his support for her cause, Theo wrote, I’m sure with his connivance, to her cousin and joint ruler King Theodahad, urging him to act against her to the ultimate of murder and assuring him that she could control her husband despite his support for the Queen. In his second great attempt, after Theodora’s death from cancer and the damaging of the empire by plague (An unusually severe plague as Edward Luttwak, among others, notes and from more modern analysis, far more deadly perhaps than past historians thought.) , Justinian tried to repair his past diplomatic failure by turning to Amada’s daughter the lovely and brilliant Mathusada. This time he hit upon a fine solution. His favored successor, his nephew Germanus, had married Mathusada (she’d been brought to Constantinople by Belisarus with her first husband the defeated Gothic King Vitiges), offering a chance to use her family connections to placate the Goths, perhaps even leading to a revival of the Western Empire under Germanus, though more likely he hoped the honor of a ruler next in line to the Roman throne, husband to their Queen and likely to father a Roman-Goth successor, would do the trick. Justinian was, if anything, perhaps only too determined to keep the costs of conquest to the minimum necessary…And again, willing at several points to concede to a divided Roman-Gothic Italy to hold some of his gains.
But to get on to the question at hand, it’s entirely possible that had circumstances allowed, Belisarus might have been kept on in Italy to consolidate the conquest. It’s doubtful Justinian believed that Beli was plotting to either revive the Western throne or seize his but Theodora, fearful of a future with Justinian gone and she friendless, was willing to entertain the notion and it was probably in part to placate her that Belisarus was recalled in 540. Justinian had granted him a Triumph, the first in centuries, for the conquest of Africa but no such honor awaited him this time, though the Persian front situation seriously demanded his attention. Lets assume Justinian’s primary motive was military need and say the Persians chose to continue the peace treaty without threat, perhaps due to troubles in the Empire or on the northeast Asian borders. Belisarus persuades Goths to accept the conquest, perhaps even puts a Goth in as a key administrative but militarily powerless figure. Plague being dodged by luck in Egypt, Justinian gets to employ his skills and the Goths receive Roman citizenship in the Empire in exchange for loyalty oaths and joining the army and even the Roman Senate in controlled numbers. Belisarus rebuilds an army of Italian Romans, again under careful limitations but enough to back up his forces for the defense of Italy.
The final piece is the marriage of Germanus and Mathusada. Justinian seizes on this as the best way to bury all animosity and Theodora decides a Germanus ruling Italy is better than one in Constantinople awaiting a chance to succeed. Ahead of schedule as no further troops are required, in about 545-6 the royal couple is sent to Sicily and safely arrive in Italy. Germanus is proclaimed Caesar and perhaps Praetorian Prefect of the western provinces, though not Augustus of the West, though he is the recognized successor. Mathusada is acknowledged Queen of the Goths, with some but limited authority. Justinian focuses on the peaceful integration of the Ostrogoths to the Empire and the reintegration of Italy, boosted greatly by a stabilized Africa. Belisarus continues as Chief of Soldiers in the West till after Germanus’ arrival and then peacefully returns to Constantinople and his deserved second Triumph. Germanus is able to make use of the threat of Frankish invasion to unify Roman and Goth for defensive war, with Totilla becoming a Senator and an important administrator in Italy, finally a trusted and skilled army general.
After overawing a Persian threat, Belisarus is asked to undertake the conquest of Spain, and wins the support of young Goths eager for adventure and reward to swell his army’s ranks. He works well with the elderly Roman commander in the field, Liberius, and Germanus in Italy supports the campaign. Spain is largely secured by 550-2 and Britain sends word from several of the embattled former British-Roman leaders that help from the Empire would be greatly appreciated. Belisarus is urged by Justinian, just recovered from the loss of Theodora, to send some sort of help and the first Roman troops since 406 arrive in western Britain, about 1000, primarily to scout the place and report on chances for reconquest. The west Britains are eager for imperial support and the expedition is successful enough to help them secure a fair amount of Wales and southwest Britain. Southern Gaul is now restive though the Visigothic kingdom’s remains in Gaul, supported by the Franks, firmly crush any clear efforts to call for reunification. Feeling he’s done enough and even southern Gaul is a task for the next generation an exhausted Belisarus receives permission to return home where later he is successful in commanding the Danubian frontier and driving back several large scale raids. Germanus proves a fine and popular Caesar of the West and lives to succeed Justinian as Augustus in 565 by which time Italy is not only well integrated into the Empire but there is growing eagerness on the part of young Romans and Gothic Romans to expand and retake Gaul and the rest of Britain. A fearful Visigoth kingdom, crippled badly by loss of Spain, is overrun by the Franks who maintain hostility to the Empire. More of Britain is secured but poor communications limit what can be done and the regained territory is allowed to run largely as a client kingdom of the Empire. The last task put on Belisarus is as Caesar of the West, largely holding the seat for Germanus’ young son, now a teen, as a favor to his friend and fighting comrade the Augustus Germanus, but he performs well, further consolidating imperial control and appointing trusted Romanized Goths to various high positions, dying in 570 or thereabouts. Gothic loyalty is further secured by affection for their beloved Queen Mathusada and her son, the future Augustus, Germanus the Younger.
