These were largely amphibious operations, made possible by the control of the Mediterranean waterways, and the fleet played a vital role in carrying supplies and reinforcements to the widely dispersed Byzantine expeditionary forces and garrisons.

In this effort the new Muslim elite, which came from the inland-oriented northern part of the Arabian peninsula, largely relied on the resources and manpower of the conquered Levant (especially the Copts of Egypt), which until a few years previously had provided ships and crews for the Byzantines.

[38] The Arab governor Musa bin Nusair built a new city and naval base at Tunis, and 1,000 Coptic shipwrights were brought to construct a new fleet, which would challenge Byzantine control of the western Mediterranean.

[75] At the same time, however, the Muslim presence in Cilicia was strengthened, and Tarsos became a major base for land and seaborne attacks against Byzantine territory, especially under the famed emir Yazaman al-Khadim (882–891), despite the heavy defeat of one of his raids before Euripos.

[91] A year later, however, a huge expedition of 112 dromons and 75 pamphyloi with 43,000 men, that had sailed under Himerios against the Emirate of Crete, not only failed to recover the island,[92] but on its return voyage, it was ambushed and comprehensively defeated by Leo of Tripoli off Chios (October 912).

[104] These conquests removed the threat of the once mighty Muslim Syrian fleets, effectively re-establishing Byzantine dominance in the Eastern Mediterranean so that Nikephoros Phokas could boast to Liutprand of Cremona with the words "I alone command the sea".

[113] Kekaumenos, writing in c. 1078, laments that "on the pretext of reasonable patrols, [the Byzantine ships] are doing nothing else but ferrying wheat, barley, pulse, cheese, wine, meat, olive oil, a great deal of money, and anything else" from the islands and coasts of the Aegean, while they "flee [the enemy] before they have even caught sight of them, and thus become an embarrassment to the Romans".

In the East, the disastrous Battle of Manzikert in 1071 had resulted in the loss of Asia Minor, the Empire's military and economic heartland, to the Seljuk Turks, who by 1081 had established their capital at Nicaea, barely a hundred miles south of Constantinople.

Historian John Birkenmeier notes that: Byzantium's lack of a navy [...] meant that Venice could regularly extort economic privileges, determine whether invaders, such as the Normans or Crusaders entered the Empire, and parry any Byzantine attempts to restrict Venetian commercial or naval activity.

In 1177, another fleet of 70 galleys and 80 auxiliary ships under Kontostephanos, destined for Egypt, returned home after appearing off Acre, as Count Philip of Flanders and many important nobles of the Kingdom of Jerusalem refused to participate in the campaign.

This, together with a similar agreement made by Isaac II Angelos (1185–1195 and 1203–1204) with Venice the next year, in which the Republic would provide 40–100 galleys at six months' notice in exchange for favourable trading concessions, is a telling indication that the Byzantine government was aware of the inadequacy of its own naval establishment.

[145] At the same time, however, the then megas doux, Michael Stryphnos, was accused by Niketas Choniates of enriching himself by selling off the equipment of the imperial fleet,[141][146] while by the early 13th century the authority of the central government had weakened to such an extent that various local potentates began seizing power in the provinces.

Following the death of Charles of Anjou in 1285 and the end of the threat of an invasion from Italy, Michael's successor Andronikos II Palaiologos (1282–1328) assumed that, by relying on the naval strength of his Genoese allies, he could do without the maintenance of a fleet, whose particularly heavy expenditure the increasingly cash-strapped treasury could no longer afford.

[160][161] The results were quick to follow: during Andronikos' long reign, the Turks gradually took permanent possession of the Aegean coasts of Anatolia, with the Empire unable to reverse the situation,[162][163] while the Venetian fleet was able to attack Constantinople and raid its suburbs at will during the 1296–1302 war.

[164][165] Andronikos' decision aroused considerable opposition and criticism from contemporary scholars and officials almost from the outset, and historians like Pachymeres and Nikephoros Gregoras dwell long on the disastrous long-term effects of this short-sighted decision: piracy flourished, often augmented by the crews of the disbanded fleet who took service under Turkish and Latin masters, Constantinople was rendered defenceless towards the Italian maritime powers, and more and more Aegean islands fell under foreign rule—including Chios to the Genoese Benedetto Zaccaria, Rhodes and the Dodecanese to the Hospitallers, Lesbos and other islands to the Gattilusi.

"[166][167][168] After 1305, bowing to popular pressure and the need to contain the Catalan Company, the Emperor belatedly tried to rebuild the navy of 20 vessels, but although a few ships were built and a small fleet appears to have been active over the next couple of years, it eventually was disbanded again.

[169][170] In the 14th century, recurrent civil wars, attacks from Bulgaria and Serbia in the Balkans and the devastation caused by ever-increasing Turkish raids hastened the collapse of the Byzantine state, which would culminate in its final fall to the Ottoman Turks in 1453.

This he personally led in the last major foray of a Byzantine navy in the Aegean, recovering Chios and Phocaea from the Genoese and forcing various smaller Latin and Turkish principalities to come to terms with him.

Despite the evidence of considerable naval activity in this period, earlier scholars believed that the Roman navy had all but vanished by the 4th century, but more recent work has altered this picture towards a transformation into a mainly fluvial and coastal force, designed for close co-operation with the army.

[216] The capital's navy had played a central role in the repulsion of the Arab sieges of Constantinople,[212] but the exact date of the establishment of the Imperial Fleet (βασιλικὸς στόλος, basilikos stolos, or βασιλικὸν πλόϊμον, basilikon ploïmon) as a distinct command is unclear.

[247] Throughout the existence of the Empire, Byzantine crews consisted of mostly lower-class freeborn men, who were professional soldiers, legally obliged to perform military service (strateia) in return for pay or land estates.

Alongside the Mardaites, who formed a significant part of the fleet's crews, an enigmatic group known as the Toulmatzoi (possibly Dalmatians) appears in the Cretan expeditions, as well as many Rus', who were given the right to serve in the Byzantine armed forces in a series of 10th-century treaties.

[295] The accepted view is that the main developments which differentiated the early dromons from the liburnians, and that henceforth characterized Mediterranean galleys, were the adoption of a full deck (katastrōma), the abandonment of the rams on the bow in favour of an above-water spur, and the gradual introduction of lateen sails.

[355][356] Importance is also laid on matching one's forces and tactics to the prospective enemy: Leo VI, for instance, contrasted (Tactica, XIX.74–77) the Arabs with their heavy and slow ships (koumbaria), to the small and fast craft (akatia, chiefly monoxyla), of the Slavs and Rus'.

[369] Like their Roman predecessors, Byzantine and Muslim ships were equipped with small catapults (mangana) and ballistae (toxoballistrai) that launched stones, arrows, javelins, pots of Greek fire or other incendiary liquids, caltrops (triboloi) and even containers full of lime to choke the enemy or, as Emperor Leo VI suggests, scorpions and snakes (Tactica, XIX.61–65).

[371] The importance and volume of missile fire during sea combat can be gauged from the fleet manifests for the Cretan expeditions of the 10th century, which mention 10,000 caltrops, 50 bows and 10,000 arrows, 20 hand-carried ballistrai with 200 bolts myai, 'flies') and 100 javelins per dromon.

[379] "As he [the Emperor] knew that the Pisans were skilled in sea warfare and dreaded a battle with them, on the prow of each ship he had a head fixed of a lion or other land-animal, made in brass or iron with the mouth open and then gilded over, so that their mere aspect was terrifying.

Greek fire continued to be mentioned during the 12th century, but the Byzantines failed to use it against the Fourth Crusade, possibly because they had lost access to the areas (the Caucasus and the eastern coast of the Black Sea) where the primary ingredients were to be found.

[394] Inevitably however, as the Italian republics slowly moved away from the Byzantine orbit, they began pursuing their own policies, and from the late 11th century on, they turned from protection of the Empire to exploitation and sometimes outright plunder, heralding the eventual financial and political subjugation of Byzantium to their interests.

Strong and energetic emperors like Manuel Komnenos, and later Michael VIII Palaiologos, could revive Byzantine naval power, but even after landing heavy strokes against the Venetians, they merely replaced them with the Genoese and the Pisans.