Theme of the Aegean Sea Αἰγαῖον Πελάγος, θέμα τοῦ Αἰγαίου Πελάγους
Theme of theByzantine Empire
843–1204
Map of Byzantine Greece c. 900 AD, with the themes and major settlements.
Historical era	Middle Ages
• Established	843
• Fourth Crusade	1204
Preceded by Succeeded by Asia (Roman province) Islands (Roman province) Duchy of the Archipelago
Today part of	Greece Turkey

TheTheme of the Aegean Sea (Greek:θέμα τοῦ Αἰγαίου Πελάγους,thema tou Aigaiou Pelagous) was aByzantine province in the northernAegean Sea, established in the mid-9th century. As one of the Byzantine Empire's three dedicated naval themes (Greek:θέματα ναυτικᾶ), it served chiefly to provide ships and troops for theByzantine navy, but also served as a civil administrative circumscription.

The theme has its origins in thelate antique civilprovince of the "Islands" (Latin:Insulae;Greek:Nήσοι,romanized: Nēsoi), which encompassed the islands of the southeastern and eastern Aegean up toTenedos. The term "Aigaion Pelagos" appears for the first time as an administrative circumscription in the early 8th century, when seals of several of itskommerkiarioi (customs officials) are attested. One seal, dated to 721/722, even refers to an official in charge of all the Greek islands, possibly implying an extension of the old province over the islands of the northern and western Aegean as well.^[1] Militarily, the Aegean islands came under control of theKarabisianoi corps and later of theCibyrrhaeot Theme during the 7th and 8th centuries.^[2] In 726, the region participated in a rebellion against theiconoclast policies of emperor Leo III. Stephen, head of the fleet of the Cyclades islands, joined rebel leaderAgallianos Kontoskeles in a failed attack on Constantinople. From the late 8th century, two separate commands appear in the Aegean: thedroungarios of the Aegean Sea (Aigaion Pelagos), apparently controlling the northern half, and thedroungarios "of the Twelve Islands" (Dodekanesos) or "of the Gulf" (Kolpos), in charge of the southern half. The latter command eventually evolved into the theme ofSamos, while the former evolved into the theme of the Aegean Sea, encompassing both the islands of the northern Aegean as well as theDardanelles and the southern coasts of thePropontis.^[1][3][2]

The theme of the Aegean Sea must have been created in 843: its governingstrategos does not appear in theTaktikon Uspensky of 842/843, which still lists thedroungarios, but he is elsewhere attested as being active atLesbos in 843.^[4]

The theme of the Aegean Sea was a regularly organized theme, subdivided intotourmai andbanda and with a full complement of military, civil, and fiscal officials. In the areas of the Dardanelles and the Propontis, however, thedroungarios and later thestrategos of the Aegean probably shared authority with the Count of theOpsician Theme, to whose jurisdiction these territories properly belonged. The Count of the Opsicians probably retained authority over civil administration and local defence, while the Aegean theme was solely responsible for equipping ships and raising the men for fleets from these areas. A similar procedure existed in the theme of Samos as well.^[5] This view is strengthened by the fact that the Opsicians, and especially theSlavs (Sklabesianoi) forcefully settled by the Empire in the Opsician Theme, are attested serving asmarines in the 10th century.^[6]

According to EmperorConstantine VII Porphyrogennetos (r. 913–959), in the early 10th century the theme includedLesbos (the seat of thestrategos),Lemnos,Imbros andTenedos,Chios (later transferred to Samos), theSporades and theCyclades.^[7][8] According toHélène Ahrweiler, the Cyclades were probably transferred to the Aegean theme when theDodekanesos/Kolpos naval command was broken up and the theme of Samos established from it in the late 9th century.^[9] In 911, the forces of the naval theme of the Aegean are recorded as being 2,610 oarsmen and 400 marines.^[10]

The province survived until the late 10th/early 11th century, when it became progressively split up into smaller commands. As the Cyclades and Sporades, Chios and the region ofAbydos acquired their ownstrategoi, the theme of the Aegean became a purely civil province comprising only the coasts of the Propontis and the region aroundConstantinople.^[11] By the late 11th century, what remained of the old thematic fleet was incorporated into the unified imperial navy at Constantinople, under the command of themegas doux.^[12] Thereafter, some time in the 12th century, the theme of the Aegean seems to have been fused with the Opsician theme into a single province, as attested in thePartitio terrarum imperii Romaniae in 1204.^[13] The theme ceased to exist after the dissolution of the Byzantine Empire by theFourth Crusade in 1204.

• States and territories established in the 840s
• States and territories disestablished in 1204
• Themes of the Byzantine Empire
• Medieval Aegean Sea
• Byzantine navy
• 843 establishments

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• Short description matches Wikidata
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• CS1 French-language sources (fr)