Battle of Makryplagi The Battle of Makryplagi or Makry Plagi was fought between the forces of the Byzantine Empire , and the Latin Principality of Achaea . The Byzantines had been weakened and demoralized by the defection of their numerous Turkish mercenaries to the Achaeans . At Makryplagi , the Byzantines suffered a heavy defeat , which together with their defeat at the Battle of Prinitza the previous year ended their attempted reconquest of the Morea . Background . After the Battle of Pelagonia ( 1259 ) , the Byzantine emperor Michael VIII Palaiologos ( r . 1259 – 1282 ) acquired a number of fortresses in the southeastern Peloponnese ( Morea ) , ceded by the captured Prince of Achaea William II of Villehardouin ( r . 1246 – 1278 ) in exchange for his release . William also pledged to become Michael ' s vassal , but as soon as he returned to the Morea he renounced this oath , and began negotiating with the Pope and other Latin powers for a joint effort against the Byzantines . War broke out in late 1262 or 1263 , when Michael VIII dispatched an expedition to the Morea . This army was composed chiefly of Turkish mercenaries and Greek troops from Asia Minor and headed by his half - brother , the " sebastokrator " Constantine Palaiologos . Constantine enjoyed initial success , capturing much of Laconia and advancing north , aiming to take the Achaean capital , Andravida . He was defeated , however by a far smaller Latin force at the Battle of Prinitza , and his army scattered . Skirmish of Mesiskli and siege of Nikli . In early 1263 or 1264 , Constantine Palaiologos resolved to resume operations , with the final aim of subduing the Principality of Achaea for good . He assembled his troops , entered Achaean - controlled territory and advanced up to Sergiana in northern Elis , and set up his camp at a location called " St . Nicholas of Mesiskli " . William with his own troops marched to meet him , and arrayed his men ready for battle . According to the " Chronicle of the Morea " , the head of the Byzantine vanguard , the " megas konostaulos " Michael Kantakouzenos , rode forth from the Byzantine lines , but his horse stumbled and he was killed by the Achaeans . Dismayed by the death of his bravest lieutenant , the " sebastokrator " Constantine retreated and went on to lay siege to the fortress of Nikli . There , however , the Turkish mercenaries , over 1 , 000 horsemen under their leaders Melik and Shalik , confronted him and demanded that he pay them their arrears of six months . Irritated by this demand , and worried by his lack of success thus far , the " sebastokrator " angrily refused , whereupon the two chieftains deserted to William with the bulk of their men . This defection caused Byzantine morale to plummet . Constantine , feigning illness , decided to raise the siege , and departed the Morea for Constantinople , leaving the " megas domestikos " Alexios Philes and the " parakoimomenos " John Makrenos in command . The battle and aftermath . Philes now took his army and marched towards Messenia , where he occupied the pass of Makryplagi , situated near Gardiki castle at the borders of Messenia with the central Peloponnese . William , reinforced by the experienced Turkish contingent and now possessing a superior army , had marched to Messenia to defend the fertile province . The Achaean army now attacked the Byzantines , despite the fact that they held strong positions on the high ground . The first two attacks were beaten off , but the third attack , led by William ' s commander Ancelin de Toucy , broke the Byzantines , who fled in panic . The Byzantine rout was complete , and the generals Philes , Makrenos , and Alexios Kaballarios , along with many Greek nobles , were captured . The prisoners were brought to William at Veligosti ; there a noteworthy conversation took place between the Achaean prince and Philes , which illustrates the respective positions of Latins and Byzantine Greeks : when William exclaimed that this defeat was God ' s punishment on Palaiologos for violating his oaths , Philes retorted that " the Morea belongs to the Empire of Romania and is the proper heritage of the Emperor . It is instead you who have broken your oaths to the lord . " William then marched south towards the Byzantine stronghold of Mystras . He failed to take the fort , but repopulated and fortified the old city of Sparta , pillaged the surrounding province and then withdrew to Nikli . Despite his successes in averting a rapid Byzantine conquest of his principality , however , William had exhausted his realm ' s resources : the constant fighting had devastated and depopulated the country . The conflict degenerated into skirmishes on both sides before being suspended entirely . Negotiations were undertaken , in which Michael VIII proposed to wed his son and heir , Andronikos II Palaiologos ( r . 1282 – 1328 ) to William ' s daughter and heiress , Isabella . The proposal foundered at the opposition of the Achaean barons . In the years after , William sought the aid and protection of the powerful Charles of Anjou , whose vassal he became by the Treaty of Viterbo . Faced with the threat of Charles , Byzantine attention was diverted elsewhere , and William managed to avert a repeat of the large - scale Byzantine offensive against him . A prolonged period of relative tranquility followed , but internal squabbles would enable the Byzantines to resume their gradual recovery of the peninsula by the early 14th century .