From 1210 on, Michael I Komnenos Doukas was engaged in territorial expansion, chiefly at the expense of the Latin
Kingdom of Thessalonica to his east; after initial reverses, much of
Thessaly was conquered. By 1214,
Dyrrhachium and
Corfu had been recovered from the Latins as well. The traditional view of historians is that these events marked Michael I's repudiation of the allegiance he had sworn to the
Latin Empire, but historian
Filip Van Tricht argues that both Michael and later Theodore remained, at least in theory, vassals of the Latin Empire
until 1217. Michael was assassinated by a servant in late 1214 or in 1215. As Michael II was illegitimate and too young, Theodore had no trouble in sidelining the boy. According to the hagiography of St.
Theodora of Arta, the boy and his mother spent the duration of Theodore's reign exiled in the Peloponnese.
Relations with Serbia and Nicaea Theodore was capable and extremely ambitious. Notwithstanding his oath to Laskaris, he aspired not only to expand his state at the expense of Thessalonica, but to eventually recover Constantinople and revive the
Byzantine Empire with himself as its ruler. To secure his northern flank, Theodore allied himself with
Serbia and the
Albanian clans. The
Principality of Arbanon had already come in the Epirote political orbit under Michael I, and closer ties developed when its ruler,
Demetrios, died in 1215, leaving his principality to his widow, who promptly remarried the next year to a Greek
magnate,
Gregory Kamonas. Against the Serbs, Theodore abandoned Michael I's attempt to pursue a northward expansion into
Zeta, and instead pursued an alliance with the Serbian prince
Stefan II Nemanjić () that was directed towards keeping the
Bulgarians in check. The ties between Epirus and Serbia were solidified by the marriage of Theodore's brother
Manuel Komnenos Doukas to one of Stefan II's sisters . Stefan II then sought to wed one of his sons—in all likelihood his eldest son and heir,
Stefan Radoslav—to Michael I's second daughter Theodora. The
Archbishop of Ohrid,
Demetrios Chomatianos, refused to sanction the marriage due to
consanguinity—Theodora was a second cousin of Stefan Radoslav's mother,
Eudokia Angelina, a daughter of Alexios III Angelos. In 1217, Stefan II tried to circumvent this by suggesting himself as the groom to Theodora's half-sister Maria, but Chomatianos vetoed this proposal as well on similar grounds. Finally, Stefan Radoslav married Theodore's firstborn daughter
Anna in winter 1219/20. With his position thus strengthened, Theodore expanded his territory into northern
Macedonia, although it is possible that at least part of this region had already been captured by Michael I after the death of the local Bulgarian ruler
Strez in 1214. It is unclear to what extent Theodore's expansion involved direct conflict with the Bulgarian Tsar
Boril (), but by 1217 he held
Ohrid,
Prilep, and most of the plain of
Pelagonia, at least up to Strez's old capital at
Prosek, and likely beyond, approaching the
Strymon River. As the Greek historian Konstantinos Varzos has noted, the capture of Ohrid, seat of the eponymous archbishopric, was particularly important for the standing of the Epirote state and Theodore's aspirations. Theodore sponsored the election of the distinguished
canonist Chomatianos to the archiepiscopal throne in 1217, and Chomatianos would repay that support with his steadfast championing of Epirote claims to the Byzantine imperial inheritance vis-à-vis the rival claims of Nicaea. Following the Fourth Crusade, the Orthodox clergy in the two main Greek states, Epirus and Nicaea, had effectively become separated. In 1208, the Nicaeans had convened a synod and elected
Michael Autoreianos as successor to the vacant see of the
Patriarch of Constantinople. The election was uncanonical and therefore of questionable legitimacy. This in turn meant that Laskaris' imperial title was also open to challenge, as he had been crowned by the same Michael Autoreianos. Already under Michael I, two local synods of bishops had emerged in the Epirote domains to carry on administration of the Church, largely independent of the Patriarch, one at
Naupaktos under
John Apokaukos, and one at Ohrid under Chomatianos. The more ambitious Chomatianos soon became the pre-eminent "western" bishop, and sought to strengthen the
de facto Epirote autonomy in ecclesiastical affairs, including the appointment of bishops for the local sees without the Patriarch's interference. This policy, which dovetailed with Theodore's own ambitions of independence from and rivalry towards Nicaea, brought the two branches of the Greek Church to an open quarrel, as the Nicaea-based patriarch
Manuel I Sarantenos began appointing bishops of his own to Epirote sees, whom the Epirotes refused to accept. Despite his close ties to Epirus, Stefan II Nemanjić exploited the Epirote–Nicaean rivalry to his advantage to secure
autocephaly for the
Serbian Church, which traditionally had been under the jurisdiction of the Archbishop of Ohrid. Brushing aside Chomatianos' vehement objections, Stefan managed to have his brother
Rastko, renamed Sava, consecrated by Manuel Sarantenos as autocephalous archbishop of Serbia in 1219. Theodore took care not to let the quarrels of the churchmen affect his cordial relations with the Serbian ruler. Theodore's drive into Macedonia disquieted another local strongman,
Alexius Slav, ruler of
Melnik. A sworn enemy of Boril, Alexius had been abandoned by his erstwhile ally, the
Latin Emperor,
Henry of Flanders (), who in 1213 allied himself with Bulgaria. Facing a possible attack by Theodore as well, Alexius now preferred to make common cause with him, and married a niece of Theodore's wife.
Capture of Peter of Courtenay The Epirote successes in Macedonia worried the Latins, as they opened the way to another attack on Thessalonica. The Kingdom of Thessalonica had been much weakened after the death of its founder,
Boniface of Montferrat, in 1207, since which it had been ruled by a regency for his underage son
Demetrius (). Interrupting a campaign against the Nicaeans in Asia Minor, Henry of Flanders hastened to Thessalonica. He took up contact with Boril and was preparing to march against Theodore when he suddenly died on 11 June 1216, probably of
malaria, although poisoning by his second wife
Maria of Bulgaria has also been suggested. The death of the warlike Henry, followed by that of
Pope Innocent III, the instigator of the Fourth Crusade, a month later, was a major stroke of good fortune for Theodore as it removed two of his most eminent and capable opponents. The barons of the Latin Empire then elected
Peter II of Courtenay, a cousin of King
Philip II Augustus of France, as the new Latin Emperor. Receiving news of his election, Peter assembled a small army of 160 knights and 5,500 foot and horse, and set out from France. After being crowned by
Pope Honorius III in
Rome, he set sail from
Brindisi in April 1217. Peter landed at Dyrrhachium, which he had promised to conquer and return to Venice, while his wife
Yolanda of Flanders sailed on to Constantinople. As in the
Norman invasion of
William II of Sicily () in 1185, Peter intended (after capturing Dyrrhachium) to follow the ancient
Via Egnatia to Thessalonica, wresting Albania and Macedonia from Epirote control in the process. The commonly accepted version of events is that Dyrrhachium resisted with success, and as his casualties mounted Peter was forced to raise the siege and start his march towards Thessalonica. The march proved difficult, due to both the harsh terrain and the open hostility of the local population—the Western sources (the
Annales Ceccanenses,
Richard of San Germano,
Philippe Mouskes, and the continuator of
Robert of Auxerre) also stress the loyalty of the local Albanian population to Theodore. After a few days, Theodore with his army confronted Peter. Theodore requested talks with the papal legate,
Giovanni Colonna, whom he assured of his goodwill and support. Western sources claim that Theodore offered to recognize the primacy of the
Catholic Church and the suzerainty of the Latin Empire—as well as to support Peter in his planned participation in the
Fifth Crusade—and offered the Latins food and guides through the mountains. Peter was glad to receive this unexpected help, and an agreement between the two was concluded. As soon as the Latins let their guard down, Theodore fell upon them. Peter of Courtenay, Colonna, the
Latin Bishop of Salona, Count
William I of Sancerre, and many Latin nobles were taken captive, while Peter's army scattered into small roving bands trying to survive. Akropolites, the chronicler
Ephraim, and some Western sources on the other hand claim that Dyrrhachium was captured, and are followed by some modern scholars, including the Greek
I. D. Romanos and the French
Alain Ducellier. According to this view, Theodore offered to acknowledge Peter's suzerainty after the city's fall, only to treacherously ambush and defeat him. As the historian
John Van Antwerp Fine remarks, "it is not important which version is correct"; the outcome was the same, and if lost, Dyrrhachium was quickly retaken after Peter's capture. According to Philip Van Tricht, Theodore's actions were motivated by several factors, which led him to regard Peter as a threat to himself and his principality. Peter's attempt to return Dyrrhachium to Venice, even if it had failed for the moment, boded ill for the future. Peter's recognition of the rights of Demetrius' half-brother
William VI of Montferrat over Thessalonica opened the way for William to take power there, and Theodore was loath to see Thessalonica—whose rulers still claimed suzerainty over Epirus—strengthened, particularly given the presence of his exiled nephew Michael II in the court of the Latin
Principality of Achaea. At the same time, Theodore and his court resented the increased papal interference in Greek affairs, especially in the aftermath of the mission of
Cardinal Pelagius, the previous papal legate to Constantinople, whose actions had deepened the rift between Greeks and Latins further.
Wars with the Latins and the capture of Thessalonica Whatever the true course of events, Theodore's unexpected victory echoed throughout the Greek world, and greatly enhanced his standing; even the usually hostile Akropolites was forced to admit in his history that this feat was "of great help to the
Romans". Conversely it dismayed Pope Honorius, who sent letters to the Latin princes of Greece as well as the
Doge of Venice and Peter of Courtenay's son-in-law King
Andrew II of Hungary (), urging them to engage themselves to secure the release of Peter and Colonna. He even wrote to Andrew and the French bishops to call for a crusade against Theodore, with which he also threatened Theodore in a letter. With the first contingents for the crusade assembling at
Ancona in late 1217, and the Venetians eager to profit from the crusade to recover Dyrrhachium, the pressure bore fruit: in March 1218, Colonna was released, with Theodore offering his apologies and assurances of loyalty to the Pope. Honorius then changed his policy to the point of forbidding the Doge of Venice to harm Theodore in the slightest, hoping thereby to secure the release of more prisoners. Although some of the lesser barons were freed, Peter and many of the most senior lords remained in captivity until their death. It is unknown when Peter of Courtenay died, but this was probably before September 1219. The capture of Peter of Courtenay left both major Latin states in northern Greece, Thessalonica and Constantinople, in the hands of female regents. Before arriving in Constantinople, where she gave birth to Peter's posthumous son,
Baldwin II (), Yolanda had stopped at the Peloponnese. There she quickly came to appreciate the wealth and strength of the Principality of Achaea, and arranged the marriage of her daughter Agnes to the principality's heir,
Geoffrey II of Villehardouin (). A politically astute ruler, Yolanda also secured her eastern border by offering her daughter
Maria of Courtenay in marriage to Theodore Laskaris, who had just been widowed for the second time. Before launching his final stroke against Thessalonica, Theodore also took care to secure his southern flank, by appointing his brother
Constantine Komnenos Doukas as governor in
Aetolia and
Acarnania. An energetic governor, Constantine not only effectively shielded the Epirote domains from the threat of the
Duchy of Athens, but soon recovered
Neopatras and
Lamia as well. Theodore himself turned his attention to clearing Thessaly of any remaining Latin presence, culminating in the surrender of the great
Platamon Castle in 1218. Over the next few years, one by one, Theodore captured the fortresses around Thessalonica itself. Platamon controlled the entrance to the
Thermaic Gulf, and with the surrender of
Serres in late 1221, Theodore cut the land connection between Constantinople and Thessalonica as well. Thessalonica was left thereby, in the words of John Fine, "more or less an island in the midst of Theodore's possessions". As the fall of Thessalonica appeared imminent, Pope Honorius
excommunicated Theodore, ordered an embargo on horses, troops, and supplies from the
Adriatic ports, and sent letters to Constantinople urging assistance to Demetrius. Demetrius himself went to Italy to seek aid, being received by the Pope in Rome in March 1222 and by Emperor
Frederick II () soon after. A crusade was proclaimed against Theodore, and troops began to gather in Italy. In the meantime, the Latin Empire, now under
Robert of Courtenay (), was once more embroiled in warfare with Nicaea as it supported Laskaris' brothers in their challenge against the new Nicaean emperor,
John III Doukas Vatatzes (). The first detachments of the assembling crusade, under Count
Oberto II of Biandrate, arrived at Thessalonica in summer 1222 and joined the
de facto regent,
Guy Pallavicini. Theodore now hastened his move against Thessalonica. After preliminary operations in late 1222, in early 1223 he laid siege to the city. Honorius excommunicated him again, and redoubled his effort to promote the crusade, which had come to a standstill in the meantime. At the Pope's urging, Venice and Emperor Frederick promised aid. Robert of Courtenay also pledged to assist, while Honorius called upon the Latin princes of southern Greece to join in the effort. The crusade finally assembled at Brindisi in March 1224. In his instructions to his legate, however, Honorius did not rule out the possibility of Theodore coming to terms with the Crusaders. True to his word, in April 1224 Robert of Courtenay sent an army to besiege Serres. During the siege, the Latin generals learned of the disastrous defeat of the main Latin army at the hands of John III Doukas Vatatzes at the
Battle of Poimanenon. They lifted the siege and hastened back to Constantinople, only to be intercepted by Theodore's men; most of the Latin army were killed or taken prisoner. This double disaster destroyed the Pope's plans for the crusade, as he had envisaged it to land in Theodore's rear while he was engaged with Robert's army. At the same time, the prospective leader of the crusade, William VI of Montferrat, fell ill. In November, the Pope was forced to postpone the crusade's departure for the next spring. With news of the Latin defeats and the postponement of the crusade, the exhausted defenders of Thessalonica surrendered the city to Theodore sometime in December 1224. The crusade to relieve it sailed in March 1225, and landed in Thessaly at
Halmyros. The Crusader army was soon decimated by dysentery, allegedly because the Greeks had poisoned the local water supply. William of Montferrat himself succumbed to it, and the remnants of the army left Greece. Demetrius of Montferrat still hoped to recover his realm with the help of Frederick II, but died in 1227. ==Emperor of Thessalonica==