Emperor Louis the Pious deposes several marcher officials – including Baldric, the duke of Friuli – from their offices due to their military impotence. As a result of Baldric’s deposition, the March of Friuli – which included Istria – is divided into four counties governed by their respective counts.
Conventus Aquasgrani mense februario factus est, in quo cum de multis aliis causis tum praecipuae de his, quae in Marca Hispanica contigerunt, ratio habita et legati, qui exercitui praeerant culpabiles inventi et iuxta merita sua honorum amissione multati sunt.
Similiter et Baldricus dux Foroiuliensis, cum propter eius ignaviam Bulgarorum exercitus terminos Pannoniae superioris inpune vastasset, honoribus, quos habebat, privatus et marca, quam solus tenebat, inter quatuor comites divisa est.
In February an assembly was held at Aachen at which the events in the Spanish March were given special consideration over other matters. The envoys who had commanded the army were found guilty and punished as they deserved by losing their offices.
Baldric, duke of Friuli, on account of whose cowardice the army of the Bulgars had ravaged with impunity the borderland of Upper Pannonia, was also deprived of the offices he had held and the march which he had ruled alone was divided among four counts.
[The translation, slightly modified by the editor, is based on Bernhard Walter Scholz and Barbara Rogers (trans.), Carolingian Chronicles: Royal Frankish Annals and Nithard’s Histories (Ann Arbor 1970), p. 122.]
Just several decades after this fateful event, the court chaplain of Emperor Louis the Pious known simply as The Astronomer composed the biography Vita Hludowici Pii imperatoris which features the following recollection of this 828 deposition:
Mense februario sequentis hiemis conventus habitus publicus Aquisgrani, ubi cum in aliis, tum maxime fervebat res in Marcha Hispanica nuper timorose ignominioseque peracta. Que ventilata et enucleatissime investigata, hi reperti sunt huius culpe auctores, qui ab imperatore praefecti sunt duces; hos ergo solummodo honoribus ademptis luere iussit imperator culpam huius ignavię.
Itidemque Baldrico duci Foroiuliensi dum obiceretur et probatum sit, eius ignavia et incuria vastatam a Bulgaris regionem nostram, pulsus est ducatu et inter quatuor comites eiusdem est potestas dissecta.
[Astronomus, Vita Hludowici imperatoris, ed. Ernst Tremp, Monumenta Germaniae historica, Scriptores rerum Germanicarum in usum scholarum separatim editi 64 (Hannover 1995), chap. 42, pp. 442–444.]
In February of the following winter, there was a public assembly at Aachen, where, among other things, affairs in the Spanish March, which recently were timorously and shamefully conducted, elicited heated discussion. When these issues were aired and investigated down to the smallest detail, the leaders who had been set in charge by the emperor were discovered to have been responsible for the failure. Having stripped them of their offices, the emperor ordered them to make amends for their faintheartedness.
Also, a charge was lodged and investigated against Duke Baldric of Friuli, that on account of his laxity and carelessness the Bulgarians had wasted our land. He was expelled from his duchy, and his power was divided among four of his counts.
[Thomas F. X. Noble (trans.), Charlemagne and Louis the Pious: Lives by Einhard, Notker, Ermoldus, Thegan, and the Astronomer (University Park 2009), p. 272.]
The historiography on this report from the Frankish Royal Annals is huge, especially since it is impossible to ascertain which precisely were those four counties into which Baldric's duchy dissolved due to the lack of contemporary primary sources.
The interpretations have been various and they are summarized in Krahwinkler's and Giesler's accounts (cited under Selected Bibliography).
The most widely accepted interpretation is that Baldric's expansive marcher duchy was hereby split into these four counties: Friuli, Istria, Carniola and Carantania.
According to this interpretation, the link between Istria and Friuli, (re)established following Charlemagne's annexation of the Peninsula in the final quarter of the 8th century (terminus ante quem 791, see the document here), was thus broken.
However, in some period before the middle of the 10th century, that is, before Otto I's invasion of Italy in 951 and the subsequent annexation of the "March of Verona and Aquileia" to the Duchy of Bavaria in 952 (see the primary source here), Istria returned to form part of the March of Friuli. When exactly this reunion happened cannot be ascertained due to the lack of primary sources.
The answer to this question of the reunion of Istria and Friuli directly affects the interpretation of the jurisdictional prerogatives of Count Alboin and Margrave Winther mentioned in the first half of the 10th century (see the document here and here). If one posits the reunion before the 10th century, then both Alboin and Winther would be the margraves of the March of Friuli which simply encompassed Istria as well. If the reunion happened later, then both Alboin and Winther would be the margraves of Istria, the first of their kind.
The image was downloaded from the official webpage of the Virtual Monastic Library of Lorsch.
The editor has subsequently inserted a red arrow on the folio to mark the part of the manuscript that refers to this particular passage that is hereby edited.