In the midst of the war between the Roman Empire under Emperor Justinian I and the Ostrogoths in Italy, the Roman general Belisarius plans the siege of the Ostrogothic capital Ravenna; The Po valley is blocked as Belisarius commands Vitalius, magister militum per Illyricum, to depart with his army from Dalmatia and subject the Ostrogothic towns of regio Venetia; traditionally taken as marking the Byzantine conquest of Ostrogothic Istria and the beginning of the centuries-long rule of the Eastern Roman Empire in Istria (narrative accounts from Procopius of Cesearea's History of the Wars).
Ἐπεὶ δὲ Βελισάριος Αὔξιμον εἷλε, ʹΡάβενναν πολιορκεῖν ἐν σπουδῇ ἐποιεῖτο καὶ ἅπαν τὸ στράτευμα ἐνταῦθα ἐπῆγε.
Μάγνον τε πέμψας ξὺν πλήθει υπερ πολλῷ ἐπὶ Ραβέννης ἰέναιa ἐκέλευε Πάδου τεb τοῦ ποταμοῦ τὴν ὄχθην ἀεὶ περιιόντα φυλακὴν ἔχειν, ὅπως δὴ μὴ τό λοιπὸν ἐνθένδε οἱ Γότθοι τὰ ἐπιτήδεια ἐσκομίζωνται.
Καὶ Βιτάλιος δέ οἰ ξὺν στρατῷ ἐκ Δαλματίας ἀφικόμενος ὄχθην τοῦ ποταμοῦ τὴν ἑτέραν ἑφύλασσεν.
Καὶ Βιτάλιον μὲν ἐς Βενετίους ἰόντα τὰc πλεῖστα ἐπάγεσθαι τῶν ἐκείνῃ χωρίων ἐκέλευεν, αὐτὸς δὲ Ίλδίγερα ἐπιπέμψαςd τὸν Πάσον ἐφύλαδδευ ἑκατέρωθεν, ὅπως τε οἱ βάρβαροι μᾶλλον ἀπορίᾳ τῶν ἀναγκαίων ἐνδώσαυσι καὶ τὰς ευνθήκας ποιήσονται ᾗ αὐτὸς βούλεται.
a) ἐπὶ Ραβέννης ἰέναι] Ρὑπὲρ ʹΡαβέννης ed. Haury. b) in parenthesi ed. Haury. c) ὡς ed. Haury. d) πέμψας ed. Haury.
After the capture of Auximus, Belisarius made haste to lay siege to Ravenna, and he brought up his whole army against it. He also sent Magnus with a large force beyond Ravenna, with orders to move constantly along the bank of the river Po and keep guard, with the purpose of preventing the Goths thereafter from bringing in provisions by way of the river. Furthermore, Vitalius, who had come from Dalmatia with an army to join him, was guarding the other bank of the river.
Furthermore, he [Belisarius] commanded Vitalius to go to Venetia and bring over as many of the towns of that region as possible, while he himself, with Ildiger, whom he had sent forward, was maintaining a guard over both banks of the Po, in order that the barbarians might yield more readily through lack of provisions and make the treaty as he himself wished.
[translation taken from Procopius, History of the Wars, trans. Henry B. Dewing, vol. 4 (London 1962), p. 113, 121].
Starting with Bernardo Benussi's thickly annotated account of the history of Istria during the (Early) Middle Ages, first published in 1897, this episode, as narrated by Procopius, has been traditionally taken as marking the beginning of the Byzantine rule in Istria. Namely, Vitalius, magister militum per Illyricum, once called by Belisarius to join his armies and march on Ravenna, conquered the remaining Ostrogothic strongholds in Venetia et Histria as he journeyed from Dalmatia to the plains of the River Po. To this day, this remains the most widely accepted interpretation.
It was only Stjepan Antoljak who vehemently argued against it back in 1956, stating that Procopius himself fails to mention anything about Istria and the putative conquest of this region by Vitalius' armies, which would not be the case had the Peninsula truly been conquered by the Byzantines and annexed to the (Eastern) Roman Empire. Instead, argues Antoljak, Istria was conquered by the Byzantines only in 552 by Narses whose triumphant marched from Dalmatia to Ravenna finally annexed Ostrogothic Istria to Justianian's Empire.
However, the same Procopius explicitly mentions in a subsequent passage, dated to c. 544/5, that Belisarius stopped in Pula to regroup his massive army (four thousand man according to the Byzantine historian, surely an overblown number) before marching against Totila (see the source here). Had Istria remained Ostrogothic during all this time, why would the Byzantines choose precisely this region to regroup their forces?
Antoljak found a creative solution: the fact that Belisarius sailed to Ravenna from Pula would prove that Istria (or at least the entire Peninsula but Pula) had been in the hands of the Ostrogoths because otherwise the Byzantine commander would have journeyed by land. The argument is weak at best. As Ivo Goldstein correctly argued in a direct response to Antoljak's interpretation, taking a continental path would have absolutely no advantage over the much faster and less dangerous maritime route (Ivo Goldstein, Bizant na Jadranu od Justinijana I. do Bazilija I. (Zagreb 1992), p. 27).
Carile (who did not read Antoljak) walked a middle ground and simply argued that by 544 Istria, "at least the coastal strip" was in the hands of the Byzantines (Carile, "Il Bellum Gothicum," p. 170).
Moreover, according to Procopius, all the supporters of the Romans, "as soon as they had heard that Germanus was on the way, gathered in a body in Istria, and there remained quiet, awaiting this army" (see the source here). Since Germanus was made the head of the imperial military in Italy in 550 and died soon thereafter, that would mean that Istria was outside of Ostrogothic control even before the triumphant march of 552.
What complicates the matter is the letter of Pope Pelagius I to patrician Valerianus (at times erroneously edited as directed to Narses) in which the pontiff reminds the Byzantine official of "what God did for him" during the times in which Venetia et Histria were occupied by the Ostrogoths and exposed to Frankish raids (see the source here). According to Procopius "Theudebert, the ruler of the Franks" had "without justification made some parts of Liguria and the Cottian Alps and the most of Venetia subject to the payment of tribute" (History of Wars, book 8, chap. 24, lines 6-10). Indeed, the continental part of Venetia was under Ostrogothic and Frankish control both before as well as after the triumphant march of Narses in 552/3 that effectively ended the "Gothic War": Verona and Brescia, the last Ostrogothic strongholds in Italy, surrendered to the Roman Empire only in 562/3, thus ending the age of Ostrogothic and Frankish Italy.
According to Antoljak, the pope's letter could only be addressed to Narses as it explicitly evokes his triumphant march trough Ostrogothic Venetia et Histria in 552. However, Pius M. Gassó and Columba M. Batlle, the editors of by far the best edition of Pope Pelagius I's epistolary, concluded, based on the study of all the surviving manuscript traditions, that the letter must have been originally issued to Valerianus. If that is the case, it remains a mystery what exactly the pope alluded to when he reminded the patricius Valerianus of "what God did for him" sometime between 541 and 552, the period of Frankish raids in northern Italy and Totila's kingship.
In the end, on the basis of these scarce primary sources, it cannot be decisively concluded if entire Istria became Byzantine in 539 and remained under the (Eastern) Roman Empire uninterruptedly until the middle of the 8th century. Carile's conclusion, that "at least the coastal strip" of Istria was Byzantine in the first half of the 540s is therefore the safest interpretation. Moreover, it is unclear whether Totila or Franks under King Theudebert I possessed any part of Istria, that is, if their control over continental Venetia extended to continental Istria as well: the fact that Byzantine army regrouped in Istria twice, first in 544/5 and second in 550, as reported by Procopius, speaks against a stable Ostrogothic and/or Frankish control of Istria between 541 and 552.
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The editor has subsequently marked the images with red lines in order to clearly denote the parts of the manuscript that are hereby edited.
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