John Doukas ( megas doux ) John Doukas ( , ca . 1064 – before 1137 ) was a member of the Doukas family , a relative of Byzantine emperor Alexios I Komnenos ( r . 1081 – 1118 ) and a senior military figure of his reign . As governor of Dyrrhachium , he secured the imperial possessions in the western Balkans against the Serbs . Appointed " megas doux " , he scoured the Aegean of the fleets of the Turkish emir Tzachas , suppressed rebellions in Crete and Cyprus , and then recovered much of the western coast of Anatolia for Byzantium . Biography . Early life . John Doukas was born circa 1064 , the second son of the " domestikos ton scholon " Andronikos Doukas , son of the " Caesar " John Doukas , and his wife , Maria of Bulgaria , the granddaughter of Tsar Ivan Vladislav of Bulgaria ( r . 1015 – 1018 ) . John was thus the brother - in - law of Alexios I Komnenos , who had married his sister Irene Doukaina . In 1074 , during the rebellion of the Norman mercenary Roussel de Bailleul , John , along with his elder brother Michael , was at his grandfather the " Caesar " ' s estates in Bithynia . Roussel demanded that the " Caesar " give up the two as hostages in return for releasing their wounded father , whom he held captive . The elder John Doukas agreed , and the two were imprisoned by Roussel ; Michael managed to escape , but the younger John remained with Roussel until the latter ' s defeat and capture by the Turks of Artuk later in the year . After his father died in 1077 , John remained in his grandfather ' s estates in Thrace , and was raised by him . It was there that he learned of the rebellion of Alexios Komnenos against Nikephoros III Botaneiates ( r . 1078 – 1081 ) in 1081 , and it was he who informed the " Caesar " of it . Together , they departed and joined Alexios ' s forces at Schiza , where the latter was officially proclaimed emperor . Governor of Dyrrhachium . In 1085 , when Alexios recovered the strategically important Adriatic port city of Dyrrhachium from the Normans who had occupied it , John Doukas was installed as the military governor ( " doux " ) of the local province . John remained there until 1092 , when he was replaced by John Komnenos , the son of the emperor ' s brother , the " sebastokrator " Isaac . His tenure was apparently very successful . John repelled the Serbian incursions from Duklja and Raška , and even , according to Anna Komnene , captured the Dukljan king Constantine Bodin ( r . 1081 – 1101 ) , before restoring him to power as a client of the Byzantine Empire . Thus John managed to restore order in the region of Albania and Dalmatia , which had suffered greatly during the Byzantine – Norman wars of the previous years . Surviving correspondence from the archbishop Theophylact of Ohrid is a testimony to his success ; after John ' s departure from the post , Theophylact expressed nostalgia for the time of his governorship and asked for his advice . Appointment as " megas doux " and campaigns against the Turks . After being recalled to Constantinople in 1092 , John was appointed to the post of " megas doux " , i . e . commander - in - chief of the Byzantine navy . Although he is the first known " megas doux " and hence usually credited as the first to hold the post , there is evidence of its existence already in late 1085 , although its holder is not named . As " megas doux " , John was tasked with countering the naval threat posed by the Turkish emir Tzachas of Smyrna . Tzachas , formerly a Byzantine vassal , had built a fleet of his own and had seized several Aegean islands , raided others , and even had himself proclaimed " basileus " ( emperor ) . After participating in a synod that condemned Leo of Chalcedon , John set forth to take back the island of Mytilene . His troops marched along the Anatolian coast to the point opposite the island , whence they crossed over . The fleet , which under Constantine Dalassenos had already recovered Chios , was to meet him there . The combined Byzantine force laid siege to Mytilene for three months , when Tzachas offered to cede the island in exchange for safe passage back to Smyrna . John agreed , but as the Turks set sail , Dalassenos , who with his ships had just arrived , attacked them . Tzachas managed to escape , but most of his fleet was captured or sunk . After this victory , John Doukas reinforced the defences of Mytilene and then led his fleet to recover the islands Tzachas had conquered , before returning to Constantinople . Upon his return to Constantinople , he was tasked ( late 1092 / early 1093 ) , along with Manuel Boutoumites , with the suppression of the revolts in Crete by Karykes and in Cyprus by Rhapsomates . The rebellion of Karykes was subdued easily , as the news of the imperial fleet ' s approach caused a counter - coup that overthrew him . At Cyprus , Rhapsomates ' s initial resistance was overcome , and he himself was captured soon after . Eumathios Philokales was installed as the island ' s new governor , and the fleet returned to Constantinople . In 1097 , after the surrender of Nicaea to the Byzantines , Alexios named John as commander - in - chief of the Byzantine army in Anatolia , and tasked with recovering the Aegean littoral from the Turks . To avoid conflict and facilitate negotiations , he was given custody of the wife of the sultan of the Seljuk Sultanate of Rum Kilij Arslan I ( r . 1092 – 1107 ) and the daughter of Tzachas , who had been captured at Nicaea . John gave command of the fleet to Kaspax , and marched against Smyrna . After a short siege , Tzachas agreed to surrender the city in exchange for his safe departure and guarantees of the inhabitants ' safety . The " megas doux " readily accepted and took possession of the city , naming Kaspax as its governor . Even before Kaspax could assume his duties however , he was murdered by a Muslim , and the enraged sailors of the fleet massacred the people of the city . John Doukas was unable to restrain them , and restored order only after the massacre had run its course . He then left the experienced general Hyaleas behind as " doux " of the city along with the entire fleet to secure the city , and continued his campaign . From Smyrna , John marched south to Ephesus . There , he defeated the Turkish garrison after a long battle , and took 2 , 000 captives , who were resettled in the Aegean islands . Petzeas was installed as " doux " of Ephesus , and John with his army turned inland . He took the cities of Sardeis and Philadelphia , which he entrusted to Michael Kekaumenos , and reached Laodicea , which opened its gates to him . From there , he marched to the fortresses of Choma and Lampe , installing Eustathios Kamytzes as governor , and reached Polybotos , where most of the Turks who had survived at Ephesus had fled . Having caught them by surprise , Doukas ' s army defeated them and took much booty . Later life . John Doukas is no longer mentioned in the " Alexiad " after his 1097 campaign . It is , however , known from monastic documents that at some point he retired to a monastery and assumed the monastic name Antony . The date of his death is also not known , but in a " typikon " dated to 1110 – 1116 he is mentioned as being alive , while in another " typikon " of 1136 , he is explicitly mentioned as having died .