The 14th century was marked by two extremely violent civil wars which broke out in the Macedonian and Thracian regions. Their origin lay in dynastic problems, though more deep-seated causes are to be found in changes occurring in the social structure. In both instances the aristocracy was in conflict with the younger generation of military cadres, who were supported by the farmers and especially by the up-and-coming class of townspeople and merchants.
These civil wars resulted in great upheavals in urban centres and hastened the desertion of the countryside and the decline of state revenues. The fact that the opposing factions had frequently sought the help of Serbs and Turks gave the latter opportunities to meddle in domestic matters concerning the already weakened Byzantine state and promoted the settlement of groups of these peoples on the Greek Peninsula.
During the first civil war (1321-1329) the emperor Andronikos II, representing the aristocratic families of Constantinople, ranged himself against his grandson Andronikos III, who drew his support from the younger generation of the military and from the inhabitants of the countryside and provincial towns.
The second civil war (1341-1354) was fought between a group of civil office-holders who supported the emperor John V, then a minor, and John Kantakouzenos, who had attracted to his side senior army officers and aristocrats who saw their privileged status to be at risk. One of the consequences of the widespread social disturbance arising from the second civil war was the revolt of the Zealots, who for a short time seized power in Thessalonike.