In 1259, the Byzantine emperor Michael VIII Palaiologos captured William II of Villehardouin, Prince of Achaea, at the Battle of Pelagonia. As the price of release, William surrendered several key fortresses in the southeastern Peloponnese — the peninsula the Byzantines called the Morea — and pledged himself as Michael's vassal. He broke that oath almost immediately upon returning to his own territory, beginning negotiations with the Pope and other Latin powers against Constantinople. War followed in late 1262 or 1263, when Michael dispatched an army under his half-brother, the sebastokrator Constantine Palaiologos, composed chiefly of Turkish mercenaries and Greek troops from Asia Minor. Constantine made early gains, capturing much of Laconia, but a far smaller Achaean force defeated him at the Battle of Prinitza, scattering his army. The reconquest that Michael had imagined was already going badly.

Constantine resolved to try again in early 1263 or 1264. He assembled his forces, advanced into Achaean-held territory toward northern Elis, and set his camp near a place called St. Nicholas of Mesiskli. The campaign's first blow fell before battle was even joined: the head of the Byzantine vanguard, the megas konostaulos Michael Kantakouzenos, rode forward from his lines, his horse stumbled, and he was killed by the Achaeans. Dismayed, Constantine withdrew to besiege the fortress of Nikli instead. There, over a thousand Turkish cavalry under their leaders Melik and Shalik confronted him demanding six months' back pay. Constantine refused. The Turkish force promptly defected to William's side. Demoralized, and feigning illness, Constantine abandoned the campaign and sailed for Constantinople, leaving the megas domestikos Alexios Philes and the parakoimomenos John Makrenos in command of an army that had already lost its best troops and its best lieutenant.

Philes marched what remained of the army toward Messenia and occupied the pass of Makryplagi, near Gardiki Castle, on the border between Messenia and the central Peloponnese. Elevated ground, a defensible position, natural chokepoints — he had chosen well. William, now reinforced by the experienced Turkish cavalry that had switched sides, led his superior army to meet the Byzantines. He attacked uphill. The first charge was repulsed. The second also. On the third assault, William's commander Ancelin de Toucy broke the Byzantine line, and the army that Philes had positioned so carefully collapsed into a rout. The generals Philes, Makrenos, and Alexios Kaballarios were all captured, along with many Greek nobles, and brought to William at Veligosti.

The Chronicle of the Morea records what happened next at Veligosti, and it deserves to be heard directly. When William told Philes that this defeat was God's punishment on Emperor Palaiologos for breaking his oaths, the captured general replied: '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.' Two men, one victorious and one in chains, each entirely certain that the land beneath them belonged to his side. William then marched south toward Mystras, failed to take it, pillaged Sparta's territory, and eventually exhausted both his resources and his army. The Peloponnese settled into a prolonged stalemate — neither Byzantine reconquest nor Frankish security fully achieved. Makryplagi was the last large-scale Byzantine offensive push in the region for decades. The Byzantines would begin recovering the peninsula only gradually, and only in the early fourteenth century.