A fourth state, known in historiography as the Latin Empire, was established by an army of Crusaders and the Republic of Venice after the capture of Constantinople and the surrounding environs.

But Theodore was able to capture much of northwestern Anatolia after the Bulgarian defeat of Latin Emperor Baldwin I in the Battle of Adrianople, because Henry was recalled to Europe to defend against invasions from Tsar Kaloyan of Bulgaria.

In 1211, at Antioch on the Meander, Theodore defeated a major invasion by the Seljuks, who were backing a bid by Alexios III Angelos to return to power.

Vatatzes prevailed over their combined forces, however, in the Battle of Poimanenon, securing his throne and regaining almost all of the Asian territories held by the Latin Empire in the process.

With Trebizond lacking any real power, Nicaea was the only effective Byzantine state left, and John III expanded his territory across the Aegean Sea.

Theodore II Laskaris, John III's son, faced invasions from the Bulgarians in Thrace, but successfully defended the territory.

He allied with Genoa, and his general Alexios Strategopoulos spent months observing Constantinople in order to plan his attack.

[10] The territories of the former Empire of Nicaea were stripped of their wealth, which was used to rebuild Constantinople and to fund numerous wars in Europe against the Latin states and Epirus.

The usurpation of the legitimate Laskarid ruler John IV Laskaris by Michael VIII Palaiologos in 1261 alienated much of the populace against the restored Byzantine Empire at Constantinople.

The court of the Nicene state widely used the term "Hellenes" instead of the earlier "Romans" to describe its Greek speaking population.

[14] Some scholars see the Nicene empire period as an indication of rising ethnic Hellenic consciousness and Greek nationalism.

[15] In the official ideology, the traditional view of Byzantium as the Roman Empire was not overturned, as the usage of the word Rhomaioi for subjects of the Nicene emperors demonstrates.

[16] The ideology of 13th-century Nicaea was characterized by belief in the continued significance of Constantinople and the hope to recapture the city, drawing less on claims of political universalism or Hellenic nationalism than on Old Testament ideas of Jewish providence.

The emperor in this period is frequently compared to Moses[17] or Zorobabel, or even as the "Pillar of Fire" that guides God's people to the Promised Land, e.g. in a speech delivered by Theodore I Laskaris, written by Niketas Choniates.

This evidence has helped to strengthen the view of some scholars, such as A. E. Vacalopoulos, who see these references, combined with a re-evaluation of Byzantium's classical past, to be the genesis of Greek nationalism.

[20] With the loss of Constantinople, this comparison played on the idea of "Hellenes" surrounded by barbarians; Choniates equated the Seljuk sultan killed by Theodore I with Xerxes, and Patriarch Germanos II recalled the victory of John III Vatatzes as another battle of Marathon or Salamis.

[21] In much the same way, Theodore II Laskaris compared his father's victories to those of Alexander the Great and proceeded to extol the martial values of contemporary "Hellenes".

In addition, unlike Vacalopoulos,[24] Beaton sees not the birth of Greek nationalism, but rather an embryonic "ethnic" awareness, primarily based around language.