Leo Gabalas was a Byzantine Greek

Byzantine Greeks

Byzantine Greeks or Byzantines is a conventional term used by modern historians to refer to the medieval Greek or Hellenised citizens of the Byzantine Empire, centered mainly in Constantinople, the southern Balkans, the Greek islands, Asia Minor , Cyprus and the large urban centres of the Near East...

 magnate, who in 1204, with the dissolution of the Byzantine Empire

Byzantine Empire

The Byzantine Empire was the Eastern Roman Empire during the periods of Late Antiquity and the Middle Ages, centred on the capital of Constantinople. Known simply as the Roman Empire or Romania to its inhabitants and neighbours, the Empire was the direct continuation of the Ancient Roman State...

 by the Fourth Crusade

Fourth Crusade

The Fourth Crusade was originally intended to conquer Muslim-controlled Jerusalem by means of an invasion through Egypt. Instead, in April 1204, the Crusaders of Western Europe invaded and conquered the Christian city of Constantinople, capital of the Eastern Roman Empire...

 seized the island of Rhodes

Rhodes

Rhodes is an island in Greece, located in the eastern Aegean Sea. It is the largest of the Dodecanese islands in terms of both land area and population, with a population of 117,007, and also the island group's historical capital. Administratively the island forms a separate municipality within...

. There he established there a separate, sovereign principality, which extended over the nearby Aegean islands

Aegean Islands

The Aegean Islands are the group of islands in the Aegean Sea, with mainland Greece to the west and north and Turkey to the east; the island of Crete delimits the sea to the south, those of Rhodes, Karpathos and Kasos to the southeast...

, claiming the titles of "Caesar

Caesar (title)

Caesar is a title of imperial character. It derives from the cognomen of Julius Caesar, the Roman dictator...

" and "Lord of Rhodes and the Cyclades

Cyclades

The Cyclades is a Greek island group in the Aegean Sea, south-east of the mainland of Greece; and a former administrative prefecture of Greece. They are one of the island groups which constitute the Aegean archipelago. The name refers to the islands around the sacred island of Delos...

".

In 1226, the Nicaean emperor

Empire of Nicaea

The Empire of Nicaea was the largest of the three Byzantine Greek successor states founded by the aristocracy of the Byzantine Empire that fled after Constantinople was occupied by Western European and Venetian forces during the Fourth Crusade...

 John III Vatatzes launched an expedition against him and defeated him, forcing him to acknowledge Nicaean suzerainty. Gabalas remained in control of Rhodes however, and soon began reasserting his independence. In 1233, a new Nicaean expedition against him under Andronikos Palaiologos failed. In the very next year Gabalas signed an alliance with Venice

Republic of Venice

The Republic of Venice or Venetian Republic was a state originating from the city of Venice in Northeastern Italy. It existed for over a millennium, from the late 7th century until 1797. It was formally known as the Most Serene Republic of Venice and is often referred to as La Serenissima, in...

 directed against Nicaea, and even provided support to the Venetians against the Nicaean-sponsored rebellion of the Greek inhabitants of Crete

Crete

Crete is the largest and most populous of the Greek islands, the fifth largest island in the Mediterranean Sea, and one of the thirteen administrative regions of Greece. It forms a significant part of the economy and cultural heritage of Greece while retaining its own local cultural traits...

. Leo ruled Rhodes until his death in 1239/1240, when he was succeeded by his brother John Gabalas.