To a lesser extent, the conflict acquired religious overtones; Byzantium was embroiled in the Hesychast controversy, and adherence to the mystical doctrine of Hesychasm was often equated with support for Kantakouzenos.

While Kantakouzenos was absent from Constantinople in September the same year, a coup d'état led by Alexios Apokaukos and the Patriarch John XIV secured the support of Empress Anna and established a new regency.

[2] During Andronikos' long reign, the remaining Byzantine possessions in Asia Minor slowly fell to the advancing Turks, most notably the newly established Ottoman emirate.

[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 chronic malaria.

Nevertheless, despite the lack of any formal appointment, Kantakouzenos placed Andronikos III's sons and the Empress-dowager Anna of Savoy under armed guard in the palace, and in a meeting of the Byzantine Senate claimed for himself the regency and governance of the state by virtue of his close association with the deceased Emperor.

This claim was disputed by Patriarch John 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.

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.

Apokaukos gathered a group of high-ranking aristocrats around him, including men such as the megas droungarios John Gabalas or George Choumnos, whom he tied to himself by marriage alliances.

[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.

[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.

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 the Italian maritime republics, while the countryside remained under the control of the conservative landed aristocracy, which derived its wealth from its estates and traditionally shunned commercial and entrepreneurial activities as unworthy of its status.

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.

[40] The more conservative and anti-Western tendencies of the aristocrats, and their links to the staunchly Orthodox and anti-Catholic monasteries, also explain their increased attachment to the mystical Hesychasm movement advocated by Gregory 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.

Apokaukos' son John 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.

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.

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.

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.

[70] Hoping for Western aid, Anna appealed to the Pope, 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.

The latter had exploited the power vacuum in the Rhodope, an effective no 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.

[88] Revenue remained scarce for the regency, the Genoese under Simone Vignoso once again seized the imperial possessions of Chios and Phocaea, and on 19 May 1346, a part of the Hagia Sophia cathedral collapsed, a terrible omen in the eyes of the capital's inhabitants.

[92] Meeting no resistance, his troops surrounded the Palace 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.

[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-autonomous appanage covering much of western Thrace, which doubled as a march against Dušan's Serbia.

[98] Of the remaining Byzantine territories, only the Zealots in Thessalonica, now an isolated exclave surrounded by the Serbs, refused to acknowledge the new arrangement, instead leading a de facto independent existence until Kantakouzenos conquered them in 1350.

Aided by the depopulation brought by about by the Black 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.

[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).

The war also led to the collapse of the centralized imperial administration in the provinces, causing control of the Thracian countryside to shift to a manorial system run by the local magnates.

[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.

[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.