| Byzantine civil war of 1341–1347 | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Part of theByzantine civil wars, the Byzantine–Serbian wars and theByzantine–Turkish wars | |||||||||
Byzantine Empire at the start of the civil war (1341) | |||||||||
| |||||||||
| Belligerents | |||||||||
Regents: Allies: Zealots of Thessalonica Bulgaria Principality of Karvuna | Allies: Beylik of Saruhan Principality of Albania Principality of Muzaka | ||||||||
| Commanders and leaders | |||||||||
Ivan Alexander Momchil †(1344–1345) | Andrea II Muzaka | ||||||||
TheByzantine civil war of 1341–1347, sometimes referred to as theSecond Palaiologan Civil War,[1] was a conflict that broke out in theByzantine Empire after the death ofAndronikos III Palaiologos over the guardianship of his nine-year-old son and heir,John V Palaiologos. It pitted on the one hand Andronikos III's chief minister,John VI Kantakouzenos, and on the other aregency headed by the Empress-DowagerAnna of Savoy, thePatriarch of ConstantinopleJohn XIV Kalekas, and themegas douxAlexios Apokaukos. The war polarized Byzantine society along class lines, with the aristocracy backing Kantakouzenos and the lower andmiddle classes supporting the regency. To a lesser extent, the conflict acquired religious overtones; Byzantium was embroiled in theHesychast controversy, and adherence to themystical doctrine ofHesychasm was often equated with support for Kantakouzenos.
As the chief aide and closest friend of Emperor Andronikos III, Kantakouzenos became regent for the underage John V upon Andronikos's death in June 1341. While Kantakouzenos was absent fromConstantinople in September the same year, acoup d'état led by Alexios Apokaukos and the Patriarch John XIV secured the support of Empress Anna and established a new regency. In response, Kantakouzenos' army and supporters proclaimed him co-emperor in October, cementing the rift between himself and the new regency. The split immediately escalated into armed conflict.
During the first years of the war, forces of the regency prevailed. In the wake of several anti-aristocratic uprisings, most notably that of theZealots inThessalonica, a majority of the cities inThrace andMacedonia came under regency control. With assistance fromStefan Dušan ofSerbia andUmur Beg ofAydin, Kantakouzenos successfully reversed these gains. By 1345, despite Dušan's defection to the opposition and the withdrawal of Umur, Kantakouzenos retained the upper hand through the assistance ofOrhan, ruler of theOttoman beylik. The June 1345 murder ofmegas doux Apokaukos, the regency's chief administrator, dealt the regency a severe blow. Formally crowned as emperor inAdrianople in 1346, Kantakouzenos entered Constantinople on 3 February 1347. By agreement, he was to rule for ten years as the senior emperor and regent for John V, until the boy came of age and ruled alongside him. Despite this apparent victory, subsequentresumption of the civil war forced John VI Kantakouzenos to abdicate and retire to become a monk in 1354.
The consequences of the prolonged conflict proved disastrous for the Empire, which had regained a measure of stability under Andronikos III. Seven years of warfare, the presence of marauding armies, social turmoil, and the advent of theBlack Death devastated Byzantium and reduced it to arump state. The conflict also allowed Dušan to conquerAlbania,Epirus and most of Macedonia, where he established theSerbian Empire. TheBulgarian Empire also acquired territory north of theEvros river.
In 1341, the Byzantine Empire was in a state of turmoil, and despite the restoration of the Empire's capital toConstantinople and the recovery of a measure of its former power byMichael VIII Palaiologos (r. 1259–1282), the policies implemented during his reign had exhausted the state's resources, and the Empire's strength waned under his successor,Andronikos II Palaiologos (r. 1282–1328).[2] During Andronikos' long reign, the remaining Byzantine possessions inAsia Minor slowly fell to the advancingTurks, most notably the newly establishedOttoman emirate. This caused a flood of refugees into Byzantium's European provinces, while at the same time, theCatalan Company wrought havoc in the imperial domains. Taxes also rose dramatically to finance tributes to the Empire's enemies. A combination of these failures and personal ambition moved the Emperor's grandson and heir, the youngAndronikos III Palaiologos, to revolt. Supported by a group of young aristocrats led byJohn Kantakouzenos andSyrgiannes Palaiologos, Andronikos III deposed his grandfather after aseries of conflicts during the 1320s.[3] Although successful in removing the old Emperor from power, the war did not augur well for the future, as the Empire's neighbours—theSerbs,Bulgarians,Turks,Genoese andVenetians—took advantage of Byzantine infighting to gain territory or expand their influence within the Empire.[4]

The only son of a former governor of the Byzantine holdings in theMorea, John Kantakouzenos was related to the Palaiologoi through his mother. He inherited vast estates inMacedonia,Thrace andThessaly, and became a childhood friend and the closest and most trusted advisor of Andronikos III.[5] During Andronikos III's reign (1328–1341), John Kantakouzenos acted as his chief minister, holding the office ofmegas domestikos, commander-in-chief of theByzantine army.[6] The relationship between the two remained close, and in 1330, when the heirless Andronikos III (John V was born in 1332) fell ill he insisted that Kantakouzenos be proclaimed Emperor or regent after his death.[7] Their ties were further strengthened in the spring of 1341, when the latter's eldest son,Matthew Kantakouzenos, wedIrene Palaiologina, a cousin of the Emperor.[8]
Unlike Andronikos II, who had disbanded the Byzantine army and navy, and who favoured monks and intellectuals, Andronikos III was an energetic ruler who personally led his forces in military campaigns.[4] In 1329, his first campaign against the Ottomans resulted in a disastrous defeat at theBattle of Pelekanos, after which the Byzantine position inBithynia rapidly collapsed.[9] Subsequent sorties into theBalkans were nevertheless successful in shoring up Andronikos' tottering realm. Thessaly and theDespotate of Epirus, two territories separated from the Empire after theFourth Crusade, were restored to imperial rule, almost without bloodshed in 1328 and 1337 respectively.[10] Andronikos III also rebuilt a modest fleet, which allowed him to recover the rich and strategically placed island ofChios from the GenoeseZaccaria family in 1329 as well as to claim the allegiance ofAndreolo Cattaneo, the Genoese governor ofPhocaea on the Anatolian mainland.[11] In 1335, however, Andreolo's sonDomenico captured the island ofLesbos with Genoese assistance. The Emperor led a fleet to recover it and Phocaea, and requested the aid of the Turkish emirs ofSaruhan andAydin. Saruhan sent troops and supplies, but Aydin's rulerUmur Beg came to meet the Emperor in person. It was during this encounter that Kantakouzenos and Umur established a long-lasting close friendship and alliance.[12]
A war with Serbia in 1331–1334 proved less successful for the Emperor when several towns in Macedonia were captured by the Serbs, led by the renegade Syrgiannes Palaiologos. These gains were only curtailed when the assassination of Syrgiannes and the threat of aHungarian invasion forced the Serbian ruler,Stefan Dušan, to seek a negotiated settlement.[13] The subsequent peace treaty concluded between Andronikos III and Dušan was important for the future of Byzantine-Serbian relations. For the first time, the Byzantines recognized the extensive gains the Serbs had made at the Empire's expense in the central Balkans during Andronikos II's reign. In the aftermath of the pact, Dušan also moved his seat, and with it his realm's centre of gravity, south toPrilep.[14]
Although the loss of Asia Minor proved irreversible, successes in Epirus and Thessaly led to a consolidation of the Empire in the Greek-speaking lands of the southern Balkans. Andronikos III and Kantakouzenos planned further campaigns to recover theLatin principalities of southern Greece, a project of major long-term importance, for, as the historianDonald Nicol writes, "if the whole peninsula of Greece could be united under Byzantine government then the Empire would once again be a homogeneous structure, able to stand up to the Serbians, the Italians and its other enemies. It would be small, but it would be a compact and manageable economic and administrative unit running fromCape Matapan toThessalonica and Constantinople".[8]
Following a short illness, on the night of 14–15 June 1341 the emperor Andronikos III died at the relatively early age of 44, possibly due to chronicmalaria.[15] His nine-year-old son John (John V) was the obvious successor, but he had not been officially proclaimed or crowned as co-emperor.[16] This left a legal vacuum, and raised the question of who would lead the Empire's government.[17]

According to Byzantine custom, the empress-dowager automatically headed any regency. Nevertheless, despite the lack of any formal appointment, Kantakouzenos placed Andronikos III's sons and the Empress-dowagerAnna of Savoy under armed guard in the palace, and in a meeting of theByzantine Senate claimed for himself the regency and governance of the state by virtue of his close association with the deceased Emperor. He also demanded that John V marry forthwith his own daughterHelena Kantakouzene. This claim was disputed by PatriarchJohn XIV of Constantinople, who presented a document from Andronikos dating from 1334, assigning to him the care of the imperial family in the case of his death. Only after a demonstration of the capital's troops on 20 June did Kantakouzenos secure recognition as regent and control of the reins of government, as well as maintaining control over the army as itsmegas domestikos.[18]
Nevertheless, opposition to Kantakouzenos began to coalesce around three figures: the Patriarch, a forceful man determined to have a voice in the governance of the Empire, the Empress-regent, who feared that Kantakouzenos would dispossess her son, and last but not leastAlexios Apokaukos, the ambitiousmegas doux (commander-in-chief of thenavy) and head of the bureaucracy.[19] A 'new man' promoted to high office as theprotégé of Andronikos III and possibly the richest man in the Empire by 1341, Apokaukos was distrusted by the hereditary aristocracy. The only surviving narrative accounts of the period, Kantakouzenos's memoirs and the history ofNikephoros Gregoras, with their pro-aristocracy bias, paint a very negative picture of the man.[20] According to Kantakouzenos, Apokaukos' adherence to the Patriarch's camp resulted from his ambition: Apokaukos sought further advancement by trying to convince Kantakouzenos to declare himself Emperor. When the latter refused, Apokaukos secretly switched his allegiance.[21]
In Donald Nicol's opinion, had Kantakouzenos remained at Constantinople, his authority might have remained secure. As themegas domestikos and regent however, he had the duty of dealing with the Empire's various enemies, who sought to take advantage of Andronikos' death. Dušan had invaded Macedonia, theEmir of Saruhan raided the coasts of Thrace, and TsarIvan Alexander of Bulgaria threatened war.[22] In July Kantakouzenos left the capital at the head of the army, leaving control of the government to Apokaukos, whom he still believed loyal to him. Kantakouzenos' campaign proved successful. He persuaded Dušan to withdraw and repulsed the Turkish raiders, while Ivan Alexander, threatened by a fleet from the Emirate of Aydin, renewed his peace treaty with Byzantium.[17][23] To crown this success, Kantakouzenos received an embassy of the Latin barons of thePrincipality of Achaea in the Morea. They expressed readiness to surrender the country in exchange for a guarantee of their property and rights. It was a unique opportunity, as Kantakouzenos himself recognized in his memoirs, since if successful, the Catalan-controlledDuchy of Athens was bound to follow, consolidating Byzantine control over Greece.[24][25]
At this point Kantakouzenos received grave news from Constantinople. In late August Apokaukos attempted a coup and tried to kidnap John V. Having failed, he fled to his fortified house atEpibatai, where he was blockaded by troops. Kantakouzenos returned to Constantinople in early September, where he stayed for a few weeks consulting with the Empress. On his way back to Thrace to prepare for a campaign into the Morea, he went to Epibatai, where he pardoned Apokaukos and restored him to his former offices.[26]
Kantakouzenos' second departure proved a great error. Back in the capital, his enemies moved in his absence. Apokaukos gathered a group of high-ranking aristocrats around him, including men such as themegas droungariosJohn Gabalas orGeorge Choumnos, whom he tied to himself by marriage alliances. The Patriarch, backed by Apokaukos' group and the authority of the Empress, dismissed Kantakouzenos from his offices and declared him a public enemy. Kalekas himself was proclaimed regent and Apokaukos namedEparch of Constantinople. Kantakouzenos' relatives and supporters were imprisoned or forced to flee the city, and their properties confiscated.[27] Although Kantakouzenos' wife and children were safe in his headquarters at Demotika (Didymoteicho), the regency placed his mother, Theodora, under house arrest. The privations she suffered during her imprisonment were to cause her eventual death.[28]

As the first groups of his partisans fleeing the capital arrived at Demotika, Kantakouzenos, by his own account, tried to negotiate with the new regency, but his approach was rebuffed.[29] Finally forced to take decisive action, on 26 October 1341, the army (2,000 cavalry and 4,000 infantry, according to Gregoras) and his supporters, largely drawn from the land-holding aristocracy, proclaimed Kantakouzenos Emperor. Although he still presented himself officially as a junior colleague to John V, and claimed to be only acting in the boy's name, having staked his claim on the throne, he had effectively started a civil war.[30][31] Kantakouzenos still hoped that negotiation might resolve the situation, but all his envoys were imprisoned and he and his supporters excommunicated by Patriarch John XIV. On 19 November 1341, the regency responded to Kantakouzenos' proclamation as Emperor with the formal coronation of John V.[32][33]
Reaction to Kantakouzenos' proclamation caused a rift in Byzantine society, with the rich and powerful land-holding magnates (traditionally called thedynatoi, the 'powerful ones')[34] who dominated the countryside quickly rallying to support him, while the ordinary population, often living in abject conditions and suffering under oppressive taxation, supported the Empress-dowager and the Patriarch.[35][36] Apokaukos was especially quick to capitalize upon this division and foment popular dislike for the aristocracy, by widely publicizing the immense wealth confiscated from Kantakouzenos' and his supporters' houses and estates.[37] In the words of Donald Nicol, "it was against him [Kantakouzenos] and everything that he stood for as a millionaire and landowning aristocrat that the people rose up. 'Kantakouzenism' became their war cry, the slogan of their discontent".[38]
Thus the battle lines of the civil war were drawn up between urban and rural factions. The cities, dominated by the middle-class civil bureaucracy and merchant class (the "people of the market"), favoured a more mercantile economy and close relations with theItalian maritime republics, while the countryside remained under the control of the conservativelanded aristocracy, which derived its wealth from its estates and traditionally shunned commercial and entrepreneurial activities as unworthy of its status. The lower social strata tended to support the respective dominant faction, the middle classes in the cities and the landholding magnates in the countryside.[39]
Polarization of this nature was not new in the Byzantine Empire. Evidence of competition between the landed aristocracy and the city-based middle classes in the political, economic and social spheres has been attested since the 11th century, but the scale of the conflict that erupted in 1341 was unprecedented. This class conflict was mirrored in the breakaway ByzantineEmpire of Trebizond as well, where a pro-imperial and pro-Constantinopolitan urban faction confronted the provincial landholding aristocracy between 1340 and 1349.[40] The more conservative and anti-Western tendencies of the aristocrats, and their links to the staunchlyOrthodox and anti-Catholicmonasteries, also explain their increased attachment to themysticalHesychasm movement advocated byGregory Palamas, whose views were mostly opposed in the cities.[41] Although several significant exceptions leave the issue open to question among modern scholars, in the contemporary popular mind (and in traditional historiography), the supporters of 'Palamism' and of 'Kantakouzenism' were usually equated.[42] Kantakouzenos' eventual victory also meant the victory of Hesychasm,confirmed in a synod in Constantinople in 1351. Hesychasm eventually became a hallmark of the Orthodox church tradition, although it was rejected by the Catholics as a heresy.[30][43]
The first manifestation of this social division appeared inAdrianople where, on 27 October, the populace expelled the city's aristocrats, securing it for the regency. This event was repeated over the next weeks in town after town throughout Thrace and Macedonia, as the people declared their support for the regency and against the despised forces of 'Kantakouzenism'.[44] In this hostile atmosphere, many of Kantakouzenos' soldiers abandoned him and returned to Constantinople.[45] In Demotika alone the popular uprising was quelled, and the town remained Kantakouzenos' main stronghold in Thrace throughout the war.[46]
When heavy snowfall rendered campaigning impossible during the following winter, Kantakouzenos instead sent envoys, including an embassy of monks fromMount Athos to Constantinople. However, they too were dismissed by the Patriarch.[47] By then, almost all of the Byzantine provinces and their governors had declared themselves for the regency. OnlyTheodore Synadenos, an old associate of Kantakouzenos who was the governor of the Empire's second city, Thessalonica, indicated his support. Synadenos had kept his allegiance to Kantakouzenos secret from the city's populace, and intended to surrender Thessalonica in collusion with the local aristocracy. Furthermore,Hrelja, the Serbian magnate and virtually independent ruler ofStrumica and theStrymon River valley, seemed to lean towards Kantakouzenos. Consequently, as soon as the weather improved, on 2 March 1342, Kantakouzenos left his wifeIrene Asanina, his brother-in-lawManuel Asen and his daughters to hold Demotika and marched west with his army toward Thessalonica.[48] On the way, he first attackedPeritheorion but was repelled and continued westward. Kantakouzenos was however able to take fortressMelnik, where he met with Hrelja to forge an alliance. Their two armies marched toward Thessalonica, but arrived too late to take control. As they approached the city, they were met by Synadenos and other aristocrats, who had fled after an uprising led by a radical popular party, theZealots.[49] Soon afterwards a fleet of 70 ships led by Apokaukos reinforced the city. Synadenos, whose family had remained behind in Thessalonica, defected to the regency. Apokaukos' sonJohn was appointed governor of Thessalonica, although effective power rested with the Zealots, who for the next seven years led an autonomous regime unparalleled in Byzantine history.[50]

At the same time, the regency's army campaigned in Thrace, formally taking possession of towns secured by popular revolt. With Thessalonica barred against him, his supply lines to Thrace cut, and desertions having reduced his army to 2,000 men, of whom half belonged to Hrelja, Kantakouzenos was forced to withdraw north to Serbia, where he hoped to secure the aid of Stefan Dušan. Soon after, Hrelja also deserted Kantakouzenos and joined the regency, hoping to gain control of Melnik for himself.[51] In July 1342, Kantakouzenos met Dušan nearPristina. The Serbian ruler appeared initially reluctant to form an alliance. Nevertheless, under pressure from his nobles, especially the powerfulJovan Oliver, he could not afford to miss this unique opportunity to expand south. Desperately in need of Serbian aid, Kantakouzenos apparently agreed that the Serbs could keep any town they took, despite his own later account to the contrary. According to Nikephoros Gregoras, the Serbs claimed all of Macedonia west of Christopolis (Kavala), except for Thessalonica and its environs. The only concession Kantakouzenos secured was that an exception be made for those towns that surrendered to him in person. To seal the pact, Kantakouzenos' younger son,Manuel, was to be wed to the daughter of Jovan Oliver, although after Dušan later broke the alliance, the marriage did not take place.[52] Hrelja too acceded to the pact, in exchange for the surrender of Melnik by Kantakouzenos' garrison. After Hrelja's death later that year, Melnik was seized by Dušan.[53]
In late summer 1342, Kantakouzenos, accompanied by several Serbian magnates, marched into Macedonia at the head of a Greek and Serbian force, intending to break through to his wife, who still held out at Demotika.[54] His advance was stopped almost immediately beforeSerres when the city refused to surrender, and the subsequent siege had to be abandoned after an epidemic killed most of his men, forcing him to retreat into Serbia with a rump force of barely 500 soldiers. Dušan led a more successful parallel campaign, capturing Vodena (Edessa).[55] Serbian forces capturedFlorina andKastoria shortly afterwards, thereby extending their hold overwestern Macedonia. The Serbs also expanded their control overAlbania, so that by the summer of 1343, with the exception ofAngevin-controlledDyrrhachium, all of the region appears to have fallen under Serbian rule.[56] Morale among Kantakouzenos' followers fell dramatically. Rumours circulated in Constantinople that a dejected Kantakouzenos planned to retire to Mount Athos as a monk, and riots broke out in the city in which several rich men were killed and their houses looted by the populace.[57]
In late fall, Empress Anna twice sent embassies to Dušan trying to convince him to surrender Kantakouzenos, but the Serbian ruler, seeking to extract more profit from their alliance, refused.[58] Kantakouzenos' fortunes began to improve when a delegation of the nobles of Thessaly reached him and offered to accept his authority. Kantakouzenos appointed his relativeJohn Angelos as the province's governor. Although in effect a semi-independent ruler, Angelos was both loyal and effective. He soon brought Epirus — which he had governed in Andronikos III's name in 1340 — into the Kantakouzenist camp, and even made gains in Thessaly at the expense of the Catalans of Athens.[59] Another effort by Kantakouzenos to break from Serbia into Macedonia failed before Serres.[60] In the meantime, Kantakouzenos' wife Irene called upon the aid of the Bulgarians to help relieve the blockade of Demotika by the regency's army. Ivan Alexander dispatched troops, but although they clashed with the regency's forces, they made no effort in assisting the city, instead pillaging the countryside.[61]

At this point, Kantakouzenos' position was greatly strengthened by the intervention of his old friend,Umur Bey, who in late 1342 or early 1343 sailed up theEvros river with a fleet of 300 ships and 29,000 (according to Kantakouzenos) or 15,000 (according to Turkish sources) men-in-arms and relieved Demotika both from the siege by the regency's forces and from the depredations of the Bulgarians. After pillaging Thrace for a few months, Umur was forced to retreat to Asia at the onset of winter, to which the Turks were unaccustomed.[62] This turn of events displeased Dušan, for Kantakouzenos now had an independent power base and was less reliant on the Serbian ruler's goodwill. The final rift between Kantakouzenos and Dušan occurred in April 1343, when Kantakouzenos persuaded the town ofBerroia, besieged by the Serbs, to surrender to him instead of Dušan. This was followed by the surrender of several other forts in the area to Kantakouzenos, includingServia andPlatamon. These moves strengthened Kantakouzenos' position and independence from Dušan, thereby thwarting the latter's plans for expansion. Realizing that he had little to gain by continuing to support Kantakouzenos, Dušan opened negotiations with the regency and concluded a formal alliance with them in the summer of 1343.[63]
Meanwhile, Kantakouzenos and his army camped outside Thessalonica, hoping to take the city through the aid of his supporters within the walls. Apokaukos arrived at the head of the Byzantine fleet to aid the Zealots, pinning Kantakouzenos down in Macedonia between Thessalonica and Dušan's possessions. Once again Umur of Aydin came to Kantakouzenos' assistance with a fleet carrying some 6,000 men, whereupon Apokaukos and his ships fled from the superior Turkish navy. Nevertheless, a reinforced Thessalonica was able to hold out against a siege by Kantakouzenos and Umur.[64] Although he had failed to take Thessalonica, the presence of his Turkish allies allowed Kantakouzenos to turn his attention towards Thrace. In late 1343 he left his son Manuel as governor of Berroia and western Macedonia and marched towards Demotika, relieving the city and seeing his wife for the first time in almost two years. On his way to Demotika, Kantakouzenos had seized a number of fortresses in Thrace, although another siege of Peritheorion failed. He followed up with a successful campaign that tookKomotini and other fortresses in theRhodope area.[65] Over the next couple of years, the towns and forts of Thrace came over to Kantakouzenos' camp one by one, but at great cost, as his mainly Turkish troops repeatedly plundered the countryside.[66] The shifting tide of the war did not go unnoticed in the opposing camp. In late 1344, several prominent personalities defected to Kantakouzenos, includingJohn Vatatzes, a general and relative by marriage to both the Patriarch and Apokaukos, thePatriarch of Jerusalem Lazaros, and, most importantly, Manuel Apokaukos, son of themegas doux and governor of Adrianople.[67]
"The king [Dušan] was insatiable, revelling in the civil wars of the Romans and considering this time the most advantageous to him and the greatest gift of fortune. Wherefore he descended like a flame and was spreading over the Roman cities and land, continuously enslaving them on his way, since there was nothing that could resist his assaults."
At the same time, the regency's alliance with Dušan was paying dividends for the Serbian ruler alone, as he had free rein to plunder and occupy all of Macedonia and Epirus. By the end of 1345, only Thessalonica, held by the Zealots, Serres and the surrounding region, which remained loyal to the regency, along with Berroia, which still held out under Manuel Kantakouzenos, remained outside Serbian control.[69]
These developments placed the regency in considerable difficulties. In spite of Apokaukos' adroit management of the state's finances, the devastation caused by the prolonged wars had emptied the treasury. In August 1343, Empress Anna was forced to pawn the crown jewels to Venice for 30,000ducats. In addition, Turkish ravages in Thrace led to a scarcity of food in Constantinople.[70] Hoping for Western aid, Anna appealed to thePope, promising the submission of herself, John V, Apokaukos and even the Patriarch to his authority, and began persecuting the pro-Kantakouzenists and anti-Western Palamists.[71]

In 1344, the regency concluded a further alliance with Bulgaria, which required the surrender of Philippopolis (Plovdiv) and nine other towns in northern Thrace along the river Evros. Nevertheless, after their occupation, Ivan Alexander refrained from direct action against Kantakouzenos' forces operating in southern and eastern Thrace.[72] At the same time,Momchil, a formerbrigand whom Kantakouzenos had entrusted with control over the region of Merope in the Rhodope mountains, switched over to the regency.[73] In early 1344, Kantakouzenos was deprived of Umur and the bulk of his army, who had sailed home to repel aLatin attack on his main harbour,Smyrna. On their way, the Turkish force was attacked by the Serbs underGregory Preljub, but prevailed at theBattle of Stephaniana.[74] Nevertheless, Kantakouzenos was able to ward off joint attacks by Dušan and Apokaukos until Umur returned to his aid the next spring at the head of an army of 20,000 men.[75]
Kantakouzenos and Umur raided Bulgaria, and then turned against Momchil. The latter had exploited the power vacuum in the Rhodope, an effectiveno man's land between the Serbs, Bulgarians and Byzantines, to set himself up as a quasi-independent prince, supported by a substantial force of around 5,000 men. On 7 July 1345, the two armiesclashed at Peritheorion. Momchil's army was crushed, and he himself fell in the field.[73] Soon afterwards, Dušan arrived before Serres andlaid siege to the city. Rejecting demands by Kantakouzenos to withdraw, a clash appeared inevitable until the murder of Alexios Apokaukos in Constantinople forced Kantakouzenos to direct his attention there.[76]
In early 1345, Kantakouzenos sentFranciscan friars to the regency to make an offer of conciliation, but it was rejected. Despite this show of confidence, the regency's position remained insecure. The defections of the previous winter had weakened their control of the capital, and in response Apokaukos launched a series ofproscriptions. He also ordered the construction of a new prison to house political prisoners. On 11 June 1345, while undertaking an inspection of the prison unaccompanied by his bodyguard, Apokaukos was lynched by the prisoners.[77]

When Kantakouzenos heard the news he marched towards Constantinople, urged by his supporters, who expected that the death of Apokaukos would result in the collapse of the regency. Kantakouzenos was more sceptical, and indeed the Patriarch and Empress Anna quickly brought the situation under control.[79] At the same time, Kantakouzenos suffered a series of reverses. These began when John Apokaukos, the nominal governor of Thessalonica, openly announced his allegiance to Kantakouzenos and his plans to surrender the city. He was immediately thwarted by the Zealots who rose up again and killed Apokaukos and the other Kantakouzenist sympathizers in the city.[80] Then John Vatatzes, who had defected to Kantakouzenos the year before, once more switched sides. He attempted to take some of Kantakouzenos' Turkish allies and a few Thracian cities with him, but was murdered soon afterwards.[81] Finally, Kantakouzenos lost the support of his most crucial ally, Umur of Aydin, who left with his army to confront the crusaders in Smyrna. Kantakouzenos replaced him by allying himself with the Emir of Saruhan and, more importantly,Orhan of the rising Ottoman emirate in Bithynia.[30][82]
In September 1345, after a long siege, Serres fell to Dušan. The Serbian ruler, who by now controlled about half of the pre-1341 Byzantine realm, was spurred by this success to lay his own claim on the Byzantine throne. Consequently, onEaster Sunday, 16 April 1346, he was crowned "Emperor of the Serbs and the Romans" inSkopje, thereby founding theSerbian Empire.[83] This development prompted Kantakouzenos, who had only been acclaimed Emperor in 1341, to have himself formally crowned in a ceremony held at Adrianople on 21 May, presided over by the Patriarch of Jerusalem, Lazaros. Lazaros then convened a synod of bishops to excommunicate the Patriarch of Constantinople, John Kalekas.[84] Not long afterwards, Kantakouzenos' ties with his new ally Orhan were cemented through the marriage of his daughterTheodora Kantakouzene to the Ottoman emir at an elaborate ceremony inSelymbria.[85]
For the regency, the situation had become desperate. Empress Anna's requests for aid from foreign powers proved unsuccessful, as both Orhan and thebeylik of Karasi rebuffed her overtures for assistance.[86] OnlyBalik, the ruler ofDobruja, sent an elite force of 1,000 men under his brothersTheodore andDobrotitsa, but they were routed by a Kantakouzenist army underprotostratorGeorge Phakrases.[87] The emirate of Saruhan offered a more substantial force of 6,000 men in the summer of 1346, but instead of fighting, they plundered Thrace and then defected to join Kantakouzenos' army.[88] Revenue remained scarce for the regency, the Genoese underSimone Vignoso once again seized the imperial possessions of Chios and Phocaea, and on 19 May 1346, a part of theHagia Sophia cathedral collapsed, a terrible omen in the eyes of the capital's inhabitants.[89]
By the summer of 1346, Kantakouzenos stood on the verge of victory. He left Thrace under the control of his son Matthew and moved on to Selymbria, close to Constantinople.[90] He did not attack the capital, but waited for almost a year for the city to surrender. In his memoirs, he explains that he did not want to turn his Turks on the city, although contemporaries such as Gregoras accused him of indecision and of needlessly prolonging the war.[91]
As the months passed, and the privations in Constantinople increased, the pro-Kantakouzenos faction in the capital grew as the Empress refused even to consider negotiations. Twice agents were sent to assassinate Kantakouzenos, but they failed. The Empress eventually fell out with Patriarch John Kalekas, who was deposed in a synod on 2 February 1347. On the same night, supporters of Kantakouzenos opened the disusedGolden Gate, and Kantakouzenos entered the city with 1,000 men.[92] Meeting no resistance, his troops surrounded thePalace of Blachernae, the imperial residence, the next morning, but the Empress refused to surrender for several days, still fearful of the fate that awaited her. Kantakouzenos' men grew impatient and stormed part of the palace complex, and John V persuaded his mother to accept a settlement.[93]

On 8 February 1347, the war formally ended with an agreement making Kantakouzenos senior emperor for ten years, after which he and John V would reign as equals. Kantakouzenos also promised to pardon anyone who had fought against him.[94] To seal the pact, John V married Kantakouzenos' daughter Helena, and in May, Kantakouzenos was crowned again in theChurch of St. Mary of Blachernae.[95] In the end, as Donald Nicol commented, the long conflict had been meaningless, with terms that "could have been agreed five years before and saved the Empire so much bitterness, hatred and destruction."[96]
Despite the moderation and clemency shown by Kantakouzenos in this settlement, it did not gain universal acceptance. Supporters of thePalaiologoi still distrusted him, while his own partisans would have preferred to depose the Palaiologoi outright and install theKantakouzenoi as the reigning dynasty.[97] Kantakouzenos' eldest son, Matthew, also resented being passed over in favour of John V, and had to be placated with the creation of a semi-autonomousappanage covering much of western Thrace, which doubled as amarch against Dušan's Serbia.[98] Of the remaining Byzantine territories, only the Zealots in Thessalonica, now an isolatedexclave surrounded by the Serbs, refused to acknowledge the new arrangement, instead leading ade facto independent existence until Kantakouzenos conquered them in 1350.[99]
After 1347, John VI Kantakouzenos tried to revive the Empire, but met with limited success. Aided by the depopulation brought by about by theBlack Death, Dušan and his general Preljub took Kantakouzenos' Macedonian strongholds as well as Epirus and Thessaly in 1347–1348, thereby completing their conquest of the remaining Byzantine lands in mainland Greece.[100] An attempt to break Byzantium's dependence for food and maritime commerce on the Genoese merchants ofGalata led to aByzantine–Genoese war, which ended in 1352 with a compromise peace.[101] In 1350, Kantakouzenos took advantage of Dušan's preoccupation with a war againstBosnia to recover Thessalonica from the Zealots as well as Berroia, Vodena and other Macedonian cities from the Serbs, but the Serbian emperor quickly reversed the Byzantine gains, leaving only Thessalonica in Byzantine hands.[102]
Steadily deteriorating relations between Matthew Kantakouzenos, who now ruled eastern Thrace, and John V Palaiologos, who had taken over Matthew's former domain in western Thrace, led to yet another internal conflict.Open warfare broke out in 1352, when John V, supported by Venetian and Turkish troops, launched an attack on Matthew Kantakouzenos. John Kantakouzenos came to his son's aid with 10,000 Ottoman troops who retook the cities of Thrace, liberally plundering them in the process. In October 1352, at Demotika, the Ottoman forcemet and defeated 4,000 Serbs provided to John V by Stefan Dušan.[103] This was the Ottomans' first victory in Europe and an ominous portent. Two years later their capture ofGallipoli marked the beginning of the Ottoman conquest of the Balkans, which culminated a century later in theFall of Constantinople.[104] Meanwhile, John V fled to the island ofTenedos, from where he made an unsuccessful attempt to seize Constantinople in March 1353. John VI Kantakouzenos responded by having Matthew crowned as co-emperor, but John V Palaiologos, enlisting Genoese support and relying on the declining popularity of Kantakouzenos, succeeded in entering the capital in November 1354. John VI abdicated and retired to a monastery. Matthew held out in Thrace until 1357, when he too abdicated, leaving John V Palaiologos as the sole master of arump state.[105]
"Upon the death of the young Andronikos [III], the worst civil war that the Romans had ever known broke out. It was a war that led to almost total destruction, reducing the great Empire of the Romans to a feeble shadow of its former self."
The civil war proved a critical turning point in the history of the Byzantine Empire. In the words of theByzantinistAngeliki Laiou, "after the end of the second civil war, Byzantium was an empire in name only",[107] while according to Eva de Vries-Van der Velden, it marks "the point of rupture between the 'decline' and 'the fall' of the Byzantine Empire".[108]
The Byzantines' division and reliance on foreign troops, especially the Serbs and Turks, encouraged the latter's expansionism. Stefan Dušan in particular proved adept in exploiting the civil war to expand his state at Byzantium's expense.[30][109] Aside from huge territorial losses, the prolonged conflict exhausted the Byzantine state's resources, as it brought "anarchy to the cities and devastation to the countryside" (Alice-Mary Talbot). Thrace, the largest contiguous territory remaining in the Empire, suffered such destruction that, along with Constantinople, it became dependent on grain imported from Bulgaria and theCrimea.[30][110] Trade had stopped, and the treasury contained, in the words of Gregoras, "nothing but the atoms ofEpicurus". Kantakouzenos had exhausted his own personal fortune, and Empress Anne had left the Empire heavily indebted to the Venetians. The war also led to the collapse of the centralized imperial administration in the provinces, causing control of the Thracian countryside to shift to amanorial system run by the local magnates. Despite their considerable wealth, the magnates, through exemptions or outright evasion, managed to avoid paying taxes to the imperial government.[111] In addition, the arrival in 1347 of the Black Death and its recurrent outbreaks further reduced the Empire's tax and recruitment base, curtailing its ability to reverse the Serbian territorial gains.[112]
Along with the renewal of the civil war in 1352, these factors destroyed any chance of even a modest recovery similar to that experienced under Andronikos III.[113] Thereafter, Byzantium remained under the menacing threat of stronger neighbours, unable to pursue an independent foreign policy, handicapped by a shortage of resources and riven by internal strife.[114] Nevertheless, through a combination of fortuitous external circumstances and adroit diplomacy, it survived for another century, until finally conquered by the Ottomans in 1453.[115] Only the Byzantine exclave in the Morea remained prosperous, having been spared the ravages of the civil war because of its relative isolation. The appointment of Manuel Kantakouzenos as itsdespotes in 1349 heralded the creation of the semi-independentDespotate of the Morea, which experienced the last economic and cultural flowering of the Byzantine world before it too fell to the Ottomans in 1460.[116]