Byzantine civil war of 1321 – 28 The Byzantine civil war of 1321 – 1328 was a series of conflicts fought in the 1320s between the Byzantine emperor Andronikos II Palaiologos and his grandson Andronikos III Palaiologos over control of the Byzantine Empire . Prelude to the civil war . Following the accidental murder of his brother Manuel over a love affair , the emperor Andronikos II excluded Andronikos III from the succession , while Michael IX , the son of Andronikos II and next in line for succession , died from shock over his son ' s death . 1321 : First conflict . Andronikos III had many supporters , chief among them John Kantakouzenos and Syrgiannes Palaiologos , who bought themselves governorships in Thrace , where discontent with the old emperor was high . On Easter 1321 , Andronikos III fled the capital to Adrianople , where he set up his court and initiated an uprising against his grandfather . Syrgiannes Palaiologos led a large army towards the capital , forcing the old emperor to negotiate . On 6 June 1321 a peace agreement was concluded , whereby Andronikos III was recognized as co - emperor and assigned Thrace and districts in Macedonia , while the rest , including Constantinople , remained under Andronikos II , who , as senior emperor , would also direct the empire ' s foreign policy . 1322 : Second conflict . The peace agreement of 1321 did not last long , as both Andronikoi pursued virtually independent foreign policies . Within the faction of Andronikos III a rift arose between the Syrgiannes and " megas domestikos " John Kantakouzenos . Syrgiannes felt that he had not been sufficiently rewarded for his support , and he also resented the greater favour shown by Andronikos II to Kantakouzenos . Furthermore , there is also a story that Andronikos III attempted to seduce Syrgiannes ' wife . As a result , in December 1321 Syrgiannes switched support to the old emperor , fleeing to Constantinople . Rewarded with the title of " megas doux " , he then convinced Andronikos II to resume the war . After several cities in the area of Constantinople went over to the younger Andronikos , another agreement in July 1322 restored the previous status quo . This agreement between grandfather and grandson , which left Syrgiannes in an awkward position . Having failed in his endeavours , he began plotting to assassinate Andronikos II and seize the throne for himself . The plot was foiled however , and Syrgiannes was sentenced to life imprisonment . On 2 February 1325 , Andronikos III was formally crowned as co - emperor by his grandfather . Although there was little fighting during this conflict , the effects had a major impact on the empire : constant troop movements from levied peasants reduced agricultural production and trade was severely interrupted . 1327 - 28 : Third conflict . In February 1327 a new conflict occurred between Andronikos III Palaiologos and his grandfather Andronikos II Palaiologos , but this time the Balkan countries were involved in war . On Andronikos II Palaiologos ' side stood the Serbian king Stefan Decanski and on the other ' s Bulgarian emperor Michael Shishman , as agreed by the Treaty of Chernomen . Battles were fought for the Macedonian territories and after this victories these territories along with the city of Salonika went into hands of Andronikos III Palaiologos . In January 1328 Andronikos III Palaiologos and his commander John Kantakouzenos entered Salonika . After these victories in Macedonia , Andronikos III decided to capture Constantinopole and in May 1328 he entered into city and forced his grandfather to abdicate and took power in charge . Two years later the old emperor was taken to monastery where he died on February 13 , 1332 . With Andronikos III Palaiologos ( 1328 – 1341 ) came a new generation with John Kantakouzenos as leader , who was in charge of politics while Andronikos III was in charge of army . The civil war exhausted the empire , the value of money dropped , but the new government took care of law and courts .