Michael VIII Palaiologos
|Michael VIII Palaiologos
Μιχαῆλ Η΄ Παλαιολόγος
|Emperor of Nicaea and Emperor of the Byzantine Empire|
Painting of Michael VIII
(as Emperor of Nicaea, with John IV Laskaris)
1261–1282 (with Andronikos II Palaiologos from 1272)
|Died||11 December 1282(aged 58)|
|Place of death||Pachomion, near Lysimachia|
|Predecessor||John IV Laskaris|
|Successor||Andronikos II Palaiologos|
|Consort||Theodora Doukaina Vatatzaina|
Andronikos II Palaiologos
|Father||Andronikos Doukas Komnenos Palaiologos|
|Mother||Theodora Angelina Palaiologina|
Michael VIII Palaiologos or Palaeologus (Greek: Μιχαήλ Η΄ Παλαιολόγος, Mikhaēl VIII Palaiologos; 1223 – 11 December 1282) reigned as Byzantine Emperor 1259–1282. Michael VIII was the founder of the Palaiologan dynasty that would rule the Byzantine Empire until the Fall of Constantinople in 1453. He recovered Constantinople from the Latin Empire in 1261 and transformed the Empire of Nicaea into a restored Byzantine Empire.
Road to the throne
Michael VIII Palaiologos was the son of the megas domestikos Andronikos Palaiologos by Theodora Angelina, the granddaughter of Emperor Alexios III Angelos and Euphrosyne Doukaina Kamaterina. According to Deno John Geanakoplos, Michael's ancestry could be traced back to all three imperial houses which ruled the empire in the centuries before the capture of Constantinople in 1204 by the Fourth Crusade. His mother does not appear to have played a significant role in his early life; at least for a time he was brought up by his elder sister Martha, the wife of megas domestikos Nikephoros Tarchaneiotes, although she was only ten years older than he.
At an early age he rose to distinction, serving as the governor of the Thracian towns of Melnik and Serres under the command of his father Andronikos. However, in the fall of 1253 Michael was accused before the Emperor John III Vatatzes of plotting against the throne. The only way Michael was allowed to prove his innocence was through trial by ordeal through holding a red-hot iron. When the Emperor ordered him to take hold of the red-hot metal, the young Michael answered (to use Geanakoplos' words) "with the astuteness that was to characterize his later career as Emperor": if the Metropolitan Phokas of Philadelphia, who evidently supported this proposal, could take the iron from the altar with his own hands and place it in Michael's, he would gladly receive it in faith that the truth would be revealed.
Although Michael won that round, and afterwards was married to the Emperor's granddaughter and appointed megas konostaulos of the Latin mercenaries in the employment of the emperors of Nicaea, Michael was still mistrusted. Following the death of John Vatatzes, with a few close friends Michael crossed the Sangarios River and took service with the Seljuk Sultanate of Rum. From late 1256 to 1258 he served as commander of the Christian mercenaries fighting for Sultan Kaykaus II; in that later year the Emperor Theodore II Doukas Laskaris recalled Michael, and after both exchanged oaths of loyalty and guarantees of safety, Michael returned to the service of the Emperor.
A few days after the death of Emperor Theodore Laskaris in 1258, Michael Palaiologos instigated a coup against the influential bureaucrat George Mouzalon, and seized from Mouzalon the guardianship of the eight-year old Emperor John IV Doukas Laskaris. Michael was invested with the titles of megas doux and, in November 1258, of despotēs. On 1 January 1259 Michael VIII Palaiologos was proclaimed co-emperor at Nymphaion.
In 1259 Michael VIII defeated the alliance of William II Villehardouin, Prince of Achaea, and Michael II Komnenos Doukas of Epirus at the Battle of Pelagonia, which Geanakoplos writes, "In the period immediately preceding the Nicene reconquest of Constantinople in 1261 no event was of greater importance than Michael Palaeologus' victory at Pelagonia." This not only neutralized, for the immediate time, the possibility of an attack from enemies on his Western borders, but improved Michael's situation from a mere usurper to a leader worth following.
Despite this brilliant victory, only one event could remove the stigma of usurper completely from the eyes of his subjects—recovery of Constantinople itself. Michael personally led the first attempt to capture the city in 1260, which was unsuccessful. Rumors of reinforcements for the beleagued city forced Michael to sign a one-year truce with the Latin Emperor Baldwin II that August. Realizing that he needed a navy to effectively besiege Constantinople, Michael concluded the Treaty of Nymphaeum with Genoa in March of the following year. Genoese help proved to be unneeded when Michael VIII's general Alexios Strategopoulos captured Constantinople through treachery on 25 July from Baldwin II.
News of the captured city reached Michael quickly. First to hear the news was his sister Eulogia, who awoke her brother at dawn. He was not convinced of what she told him until a messenger arrived from Strategopoulos bearing the crown and sword Baldwin had abandoned in his flight from his palace. Michael VIII entered the city on 15 August and had himself crowned together with his infant son Andronikos II Palaiologos.
When Michael VIII entered the city, its population was 35,000 people, but he succeeded in increasing it to 70,000 people by the end of his reign. Once in control of Constantinople, Michael VIII Palaiologos abolished all Latin customs and reinstated most Byzantine ceremonies and institutions as they had existed before the Fourth Crusade, repopulating the capital and restoring damaged churches, monasteries, and public buildings. He was acutely aware of the danger posed by the possibility that the Latin West, particularly his neighbors in Italy would unite against him and attempt the restoration of Latin rule in Constantinople.
In December John IV, who had been left behind at Nicaea, was blinded and relegated to a monastery. After rendering John IV ineligible for the throne, Michael VIII quickly married off John's sisters to two Italians and the third to a Bulgarian noble, so their descendants could not threaten his own children's claim to the imperial succession. Although Michael tried to keep John's blinding a secret, the news eventually leaked out and Patriarch Arsenios excommunicated Michael VIII. This ban was not lifted until six years later (1268) on the appointment of patriarch Joseph I.
Diplomacy and Conquest
In the words of Geanaklopos, "With the fall of Constantinople, the papacy suffered not only a loss of political prestige but severe damage to its spiritual authority as well. For the Greeks had now effectively reasserted their right to a church divorced from Rome. Thus it became the task of each of the six successive popes of Michael's reign to accomplish the return of the schismatics to the Roman fold." Yet Michael realized the immense influence the Curia had in the West, so he immediately dispatched an embassy to Pope Urban IV consisting of two envoys; upon reaching Italy, the men were seized, one flayed alive while the other succeeded in escaping back to friendlier territories.
Michael also approached Manfred of Sicily to achieve some kind of accord. In the summer of 1262, Michael offered to divorce his wife Theodora and marry Manfred's sister Anna. This offered failed spectacularly: not only did Anna reject his proposal, Theodora turned to Patriarch Arsenios for help. The Patriarch confronted the emperor and pressured him to abandon his plans. Michael yielded and sent Anna back to her brother with gifts. This gesture helped to secure the release of his general Alexios Strategopoulos.
Then followed a series of military setbacks. The first were in 1263. That year the emperor sent 15,000 men (which included 5,000 Seljuk mercenaries) to Morea with the goal of conquering the Principality of Achaea, but this expedition failed in a surprise rout at Prinitza. Later that year a mixed fleet fleet of 48 imperial and Genoese ships was defeated by a smaller Venetian force at the Battle of Settepozzi. The following year, the imperial forces in Morea were again defeated at Makryplagi, after the Seljuk mercenaries, who had not been paid, changed sides. The nadir of Michael's disasters came in the Spring of 1265, when an army of Tatars and Bulgars under Nogai Khan ravaging Thrace ambushed Michael Palaeologos when he was returning to Constantinople accompanied by only a few troops. Deserted by even his own officers, who fled to save their own lives, Michael was able to escape by crossing the Ganos Mountains and reaching the Marmora coast, where he happened upon two Latin ships. He quickly boarded the vessels, and two days later safely arrived at Constantinople. "Thus did Michael survive one of the narrowest escapes of his career," notes Geanakoplos.
The military advantages Michael enjoyed after capturing Constantinople had evaporated, but he would demonstrate his diplomatic skills to successfully recover from these drawbacks. After Settepozzi, Michael VIII dismissed the 60 Genoese galleys that he had hired earlier, and began a rapprochement with Venice. Michael secretly negotiated a treaty with the latter city to grant terms similar to those in the case of Nymphaeum, but Doge Raniero Zeno failed to ratify the agreement. He also signed a treaty in 1263 with the Egyptian Mamluk sultan Baibars, and Berke, the Mongol Khan of Kipchak Khanate.
Michael and Charles of Anjou
The Battle of Benevento on 26 February 1266 brought forth a new challenger to Michael, one with whom he would struggle for the rest of his life: Charles of Anjou. Michael, as Geanaklopos emphasizes, "from 1266 until shortly before his eath in 1282 ... was constrained to devote almost complete attention to the defeat of Charles, the fulfillment of whose ambition would have brought about the destruction of the Byzantine Empire and reimposition of Latin rule in Constantinople." Charles strengthened his hold on the kingdom of Sicily by defeating Conradin at the Battle of Tagliacozzo on 23 August 1268. And looking for help to restore the Latin Empire, on May 1267, Charles concluded the Treaty of Viterbo with the exiled Baldwin II of Constantinople and William II Villehardouin under the guidance of Pope Clement IV.
In many ways Michael and Charles were alike. Geanapoklos quotes Nicephorus Gregoras's comparison of the two men at length:
- Charles, motivated not by small but great ambitions, implanted in his mind like a seed the resolution of taking Constantinople. He dreamed that if he could become the master of it, he would restore the entire monarchy, so to speak, of Julius Caesar and Augustus. He was very able not only in planning what he wished to do but in easily translating his thoughts into action. Clearly he surpassed all his predecessors in the strength of his nature and intelligence.... Nevertheless, neither his actions against the Greeks nor those of Michael Palaeologus against the Latins could be brought to a successful conclusion. For the strength of both was for a long time so evenly matched that it was well said (this was the opinion of discerning people) that if at that time such an Emperor had not been directing Greek affairs, the Empire would easily have succumbed to Charles, the King of Italy [sic]; and, conversely, if such a King had not then been at the helm of Italian affairs, the hegemony of Italy would with little difficulty have passed to Michael Palaeologus.
Michael's response to the Treaty of Viterbo was to attempt to weaken papal support for it; if the Pope was convinced Charles of Anjou's invasion was a just and holy war, then the forces Michael could call on could not prevent its success. Michael returned to negotiating a union of the churches with Pope Clement IV, which he had allowed to but the latter's death in November 1268 put an end to this approach. According to Geanakoplos, only a lack of resources prevented Charles from immediately launching an attack against Michael. Looking for some restraint on Charles, Michael made a shrewd appeal to the leading ruler of the West, King Louis IX of France, and elder brother of Charles. Louis was more interested in a crusade against Muslims controlling the Holy Land than a schismatic Christian, so he convinced Charles to accompany him on his Tunisian crusade in 1270. So when King Louis died 24 August 1270, Charles came into control of the French forces; after negotiating a peace with the Emir of Tunis, Charles sailed with his troops to the port of Trapani in Sicily, at last able to attack Byzantium unblocked by any man. At this point a miracle saved Michael: a violent storm arose 22 November that practically demolished the entire fleet. "To the Greeks of Byzantium," writes Geanakoplos, "it must have seemed as if the Virgin, their protector, had saved them from disaster."
After a three year interregnum, during which Charles of Anjou attempted to sway the election, a new Pope was elected, Gregory X. When Michael restarted talks of union, Gregory proved to be less accommodating and negotiated from a position of strength. Michael attempted to reason with Patriarch Joseph and the synod of the importance of agreeing to this union, and that the principle of oikonomia (which Geanakoplos suggests is best translated here as "considerations of self-interest") required them to accede to papal demands. But despite a propaganda campaign over the Winter of 1274-1275, Michael was forced to depose Patriarch Joseph and replace him with his own supporter John Bekkos in order to obtain a grudging consent to the union.
Council of Lyons and after
Byzantine envoys presented themselves at the Second Council of Lyons 24 June 1274, where they presented a letter from the Emperor, sealed with the imperial golden bull, and two other from his son Andronikos and the Byzantine clergy. On the fourth session of the Council the formal act of union was performed. The letters were read, and for the first time in two centuries representatives of the major Eastern and Western branches of Christianity were again in communion.
Michael VIII achieved an important advantage by this union, for now he gained legitimacy both for possessing Constantinople and his claims for the lands occupied by Western invaders. Further, his antagonist Charles could not rely on the power of the pope calling for a crusade against his realm. And lastly, Pope Gregory was very favorable to Michael's proposal for a crusade against the Turks and restore ancient the Christian cities of Anatolia; however with Gregory's death (January, 1276), these plans remained nothing more than talk.
More disappointments followed as news of the Council filtered through the former Byzantine territories. While the union was opposed at all levels of society, it was especially opposed by the greater populace, led by the monks and the adherents of the deposed Patriarch Arsenios, known as the Arsenites. One of the chief anti-unionist leaders was Michael's own sister Eulogia, who fled to the court of her daughter Maria, Tsarina of the Bulgars, from where she intrigued unsuccessfully against Michael. More serious were the opposition of the sons of Michael of Epirus, Nikephoros I Komnenos Doukas and his brother John the Bastard: they posed as the defenders of Orthodoxy and gave support to the anti-unionists fleeing Constantinople. Michael at first responded with comparative leniency, hoping to win the anti-unionists through persuasion, but eventually the virulence of the protests led him to resort to force. Many anti-unionists were blinded or exiled. Two prominent monks, Meletios and Ignatios, were punished: the first had his tongue cut out, the second was blinded. Even imperial officials were harshly treated, and the death penalty was decreed even for simply reading or possessing pamphlets directed against the Emperor. "From the intensity of these disorders, tantamount almost to civil wars," concludes Geanakoplos, "it might appear that too great a price had been paid for the sake of union."
The religious situation only worsened for Michael. On 1 May 1277, John the Bastard convoked a synod at Neopatras which anathematized Emperor, Patriarch and Pope as heretics. In response, a synod was convoked at the Hagia Sophia on 16 July where both Nikephoros and John were anathematized in return. John called a final synod at Neopatras in December 1277, where an anti-unionist council of eight bishops, a few abbots, and one hundred monks, again anathematized Emperor, Patriarch and Pope.
Michael's achievements on the battlefield was more positive, although still mixed. He tried to take advantage of a civil war in Bulgaria in the late 1270s but the Byzantine armies suffered several major defeats at the hands of the peasant Emperor Ivaylo. The Emperor managed to temporarily impose his son-in-law Ivan Asen III on the Bulgarian throne but after the Byzantine defeat at Devina he had to flee. However, later Michael VIII managed to conquer the Bulgarian portion of Thrace while the internal situation of the Bulgarian Empire remained unstable. In 1275, Michael VIII sent an army against Thessaly and fleet of 73 ships to harass the Latin states in Greece. The army was crushingly defeated at the Battle of Neopatras, but the fleet won a similarly comprehensive victory at the Battle of Demetrias.
Last was his victory over Charles of Anjou in western Greece. Charles' general Hugh of Sully with 8,000 men (including 2,000 cavalry) captured Butrinto in 1280 and besieged Berat. A Byzantine army of relief under Michael Tarchaneiotes arrived in March 1281: Hugh of Sully was ambushed and captured, and his army put to flight. Geanaklopos considers most scholars do not appreciate fully the importance of this victory: "this victory marked the complete failure of the attempt to launch a land expedition against the capital. Thus ... Charles had to shift his strategy to a sea attack against Constantinople".
The Sicilian Vespers
On 22 February 1281 a new Pope was selected, Pope Martin IV, a Frenchman Geanaklopos describes as "blindly subservient" to Charles of Anjou. Once again, Charles had no clear brake on his ambitions to conquer Constantinople, and he moved swiftly to prepare for this new offensive. One early move was taken by Pope Martin, who on 18 October 1281 excommunicated Michael without any warning or provocation, thus disrupting the union of Lyons.
Charles had prepared a military force far larger than what Michael could muster. According to Marino Sanudo, Charles had 100 ships in Sicily, and 300 more in Naples, Provence, and his Greek territories, which were to carry no less than 8,000 cavalrymen. Geanakoplos cites surviving documents that attest to the supplies Charles had accumulated. One Angevin rescript, dated 28 October 1281, lists a collection of tools to be gathered for the expedition, which includes "two thousand iron mattocks, three thousand iron stakes, sledges for smashing rocks, ropes, iron shovels, axes, and kettles for boiling pitch." Another orders the delivery of "four thousand iron stakes that are under construction in Venice." A third consists of instructions to a Pisan merchant for 2,500 shields of various sizes, all to be emblazoned with his royal emblem of lilies. Allied with Charles were a long list of powers. Besides having ties of kinship with the Kings of France and Hungary, the rulers of the Serbs and Bulgars were his allies, as well as the rulers of Epirus and dissidents of the Byzantine Empire, and the leading naval power of Europe, Venice.
Obviously Michael sought allies against Charles of Anjou, but they were few. His ambassadors visited the court of Roman-German King Rudolph of Habsburg, but he was aloof. King Peter III of Aragon proved more welcoming: he had his own reasons to hate Charles. According to Geanakoplos, Peter's wife Constance was the daughter of Manfred, and for this reason peter considered Charles a usurper and Sicily the rightful property of Constance. He welcomed refugees from Sicily, most notably John of Procida, whom Peter made secretary of the royal chancery. Yet Aragon was at the other end of the Mediterranean, far from Michael.
But before Charles of Anjou could start for Constantinople, on 30 March 1282 the Sicilian Vespers struck. Charles sent four ships to handle the revolt, but when the rebels took control of Messina, he ordered the men and materiel assembled for use against Michael to besiege that city; meanwhile seventy Angevin ships at the arsenal of Messina were destroyed. Eventually Charles lifted the siege, and Peter of Aragon landed in Sicily to reclaim the island for his wife.
Beginning with Pope Martin's bull dated 18 November 1282, wherein he again excommunicates Michael -- but also Peter of Aragon, John of Procida, and Michael's emissary Benedetto Zaccaria -- as the author of the conspiracy that led to the Sicilian Vespers, Michael has been seen as the instigator of the Sicilian Vespers. Geanakoplos, while admitting that Michael was in contact with the leaders of the revolt beforehand, asserts that "Michael Palaeologus, on his part, had nothing to do with the incident at the church of Santo Spirito is beyond question."
Furthermore, Michael VIII was instrumental in instigating revolts in Crete against the Venetians, the most famous of which was led by the Hortatzoi brothers Georgios and Theodore of Mesi in Rethymnon, with a duration of six years, causing most significant harm to the Venetian occupants and economic interests of Venice. Michael VIII had aimed to eventually bring Venice, an ally of Charles of Anjou, to the table of negotiations, as he did, at his court in Constantinople.
In reconstituting the Byzantine Empire Michael VIII restored the old administration without endeavouring to correct its failures. In recovering Constantinople and investing in the defence of his European provinces, Michael VIII began to denude the Anatolian frontier of its troops and was forced to lower their pay or cancel their tax exemptions. This policy led to the gradual collapse of the frontier, which was infiltrated by Turkish bands even before the death of Michael VIII in Pachomios village, Thrace in December 1282. The Palaiologan dynasty he established ruled the Byzantine Empire for almost two centuries, longer than any other in Roman history. Also, during his reign there was a temporary naval revival in which the Byzantine navy consisted of 80 ships.
In 1253, Michael VIII Palaiologos married Theodora Doukaina Vatatzina, a grandniece of John III Doukas Vatatzes, Emperor of Nicaea. Orphaned in childhood, she was raised by her great-uncle John III, who was said to have "loved her like a daughter", and who arranged for her marriage to Michael. Their children were:
- Manuel Palaiologos (c. 1255–before 1259)
- Irene Palaiologina (c. 1256–before 1328), who married emperor Ivan Asen III of Bulgaria
- Andronikos II Palaiologos (1259–1332)
- Anna Palaiologina (c. 1260–1299/1300), who married Demetrios/Michael Komnenos Doukas, third son of Michael II of Epirus
- Constantine Palaiologos (1261–1306), who married Eirene Raoulaina his second cousin
- Theodora Palaiologina, who married King David VI of Georgia
- Eudokia Palaiologina, who married Emperor John II of Trebizond
- Theodore Palaiologos (c. 1263 – after 1310)
By a mistress, a Diplovatatzina, Michael VIII also had two illegitimate daughters:
- Euphrosyne Palaiologina, who married Nogai Khan of the Golden Horde
- Maria Palaiologina, who married Abaqa Khan of Ilkhanid Persia
|Ancestors of Michael VIII Palaiologos|
- Finlay, George, History of the Byzantine and Greek Empires, Vol 2, p. 463
- Geanakoplos, Emperor Michael Palaeologus and the West (Harvard University Press, 1959), p. 17
- Geanakoplos, Michael Palaeologus, pp. 18f
- Geanakoplos, Michael Palaeologus, pp. 23f
- Geanakoplos, Michael Palaeologus, pp. 26-30
- Geanakoplos, Michael Palaeologus, pp. 39-46
- Geanakoplos, Michael Palaeologus, p. 47
- A detailed account and analysis of the Battle of Pelagonia can be found in Deno John Geanakoplos, "Greco-Latin Relations on the Eve of the Byzantine Restoration: The Battle of Pelagonia-1259", Dumbarton Oaks Papers, 7 (1953), pp. 99-141. Geanakoplos' chapter in his Michael Palaeologus offers little new on his earlier paper.
- Geanakoplos, Michael Palaeologus, p. 78
- Geanakoplos, Michael Palaeologus, p. 119
- Donald Nicol, The Last Centuries of Byzantium, 1261–1453, second edition (Cambridge: University Press, 1993), pp. 44f
- Geanakoplos, Michael Palaeologus, p. 140
- Geanakoplos, Michael Palaeologus, pp. 140f
- Geanakoplos, Michael Palaeologus, pp. 144f
- Geanakoplos, Michael Palaeologus, pp. 151-60
- Geanakoplos, Michael Palaeologus, pp. 181f
- Geanakoplos, Michael Palaeologus, pp. 182-85
- Cambridge Illustrated History of the Middle Ages: 1250–1520, p. 304
- Geanakoplos, Emperor Michael, pp. 189f
- Geanaklopos, Emperor Michael, pp. 195-200
- Gregoras, 123, ll. 8-15; 144, ll. 16ff. Translated in Geanakoplos, Emperor Michael, p. 190
- Geanakoplos, Emperor Michael, p. 216
- Geanakoplos, Emperor Michael, p. 228
- Nicol, Last Centuries, p. 56
- Geanakoplos, Emperor Michael, pp. 258-264
- Geanakoplos, Emperor Michael, p. 278
- Geanakoplos, Emperor Michael, pp. 286-290
- Geanakoplos, Emperor Michael, pp. 264-275
- Geanakoplos, Emperor Michael, p. 276
- Geanakoplos, Emperor Michael, p. 275
- Geanakoplos, Emperor Michael, p. 309
- Geanakoplos, Emperor Michael, p. 334
- Geanakoplos, Emperor Michael, p. 340
- Geanakoplos, Emperor Michael, p. 341
- Geanakoplos, Emperor Michael, pp. 361f
- Geanakoplos, Emperor Michael, pp. 345f
- Geanakoplos, Emperor Michael, pp. 365f
- Geanakoplos, Emperor Michael, pp. 347f
- Agelarakis, P. A. (2012), "Cretans in Byzantine foreign policy and military affairs following the Fourth Crusade", Cretika Chronika, 32, 41–78.
- Geanakoplos, Deno J., Emperor Michael Palaeologus and the West (Harvard University Press, 1959)
- Nicol, Donald. The Last Centuries of Byzantium, 1261–1453 (Cambridge University Press, 1993). ISBN 0-521-43991-4
- Harris, Jonathan, Byzantium and the Crusades (Hambledon and London, 2003). ISBN 1-85285-298-4
- This article incorporates text from a publication now in the public domain: Chisholm, Hugh, ed. (1911). Encyclopædia Britannica (11th ed.). Cambridge University Press
- Charanis, Peter. "The Jews in the Byzantine Empire under the First Palaeologi." Speculum, 22 (1947), 75–77.
- Heath, Ian, Byzantine Armies, AD 1118–1461 (Osprey Publishing, 1995). ISBN 1-85532-347-8
- Oxford Dictionary of Byzantium, Oxford University Press, 1991
- Vannier, J-F. Les premiers Paléologues (Etudes prosopographiques), 1989
- Media related to Michael VIII Palaiologos at Wikimedia Commons
- Coinage featuring Michael VIII Palaiologos
Michael VIII Palaiologos
Palaiologos dynastyBorn: Unknown 1224 Died: 11 December 1282
John IV Doukas Laskaris
|Emperor of Nicaea
with John IV Doukas Laskaris (1258–1261)
Restoration of the Byzantine Empire
Baldwin II of the Latin Empire
with Andronikos II Palaiologos (1272–1328)
Andronikos II Palaiologos