Construction of Trireme Changes Naval Warfare Summary

  • Last updated on November 11, 2022

The construction of the trireme changed naval warfare, making possible the sophisticated ramming tactics that dominated Mediterranean naval warfare during the fifth and fourth centuries b.c.e.

Summary of Event

Although warships with rams appeared early in the Mediterranean region, sophisticated ramming tactics had to await the evolution of specialized warships designed specifically for optimum use of the ram. As early as the eighth century b.c.e., Greek vase paintings depict warships with rams and a single file of rowers on each side. Like most ancient warships, these vessels could cruise under sail but relied on oar power in battle. Later literary sources refer to larger and smaller versions of this type of ship: a triakontor (thirty-oared ship) with fifteen rowers per file, and a pentekontor (fifty-oared ship) with twenty-five rowers per file. With only two files of rowers at one level, these ships had roomy holds and considerable capacity for passengers and cargo in addition to their rowing crews. This roominess suited a style of warfare that involved the transport of sizable numbers of soldiers for coastal raids and boarding attacks on other ships. In naval battles between fleets, the pentekontors primarily functioned as fighting platforms from which armored soldiers, javelin throwers, and archers fought for control of immobilized adjacent vessels. Rams were no doubt used when the opportunity to hole an enemy ship presented itself, but the pentekontor’s limited rowing power restricted its effectiveness as a ram. Ameinocles Phormion Themistocles

Because the pentekontor’s length approached the ancient design limit of twenty-five to thirty rowers, in order to substantially augment rowing power, it was necessary to increase the number of files. The bireme accomplished this by putting two additional files of oar men in the hold area, so that there were now two banks of rowers on each side of the ship. The trireme, with three banks of rowers per side, simply took this concept one step further to produce a vessel with more than three times the oar power of a pentekontor.

Triremes on the water.

(Library of Congress)

For centuries, historians have argued over the exact design and rowing configuration of the trireme, but the recent construction of a functioning full-scale replica appears to settle most questions. In particular, it demonstrates that with outriggers, rowers at three different levels can operate efficiently using oars of the same length. With 170 rowers in three banks packed within its narrow, lightly built hull, the trireme sacrificed strength, stability, and cargo capacity for speed and maneuverability. An improved bronze ram at the bow’s waterline completed the transformation of the pentekontor. The result was a virtual guided missile perfectly matched to the hit-and-run ramming tactics that would rule naval warfare in the two centuries following the trireme’s widespread adoption.

Although the overall evolution from pentekontor to bireme to trireme seems clear enough, the question of the date and place of trireme’s invention is still debated. The earliest explicit report of triremes used in war refers to ships built in Egypt by the pharaoh Necho I (r. c. 672-664 b.c.e.). Because of Egypt’s proximity to Phoenicia and the later fame of Phoenician triremes, some historians attribute the innovation to the Phoenicians. Other scholars note Necho’s close relations with the Greeks and prefer to credit them with the breakthrough. According to the Greek historian Thucydides (c. 459-c. 402 b.c.e.), the earliest naval battle took place when the Corcyraeans fought the Corinthians, who were the first among the Greeks to build triremes. Thucydides also names a noted Corinthian shipwright, Ameinocles, who built four triremes for the island city-state of Samos. If these events are correctly dated to the middle and late seventh century, then Necho may well have learned about triremes from Corinth. Regardless of who is given credit for the invention, in later times both the Phoenicians and the Greeks were acknowledged as masters of trireme construction and use.

Despite its early invention and its superiority as a ramming weapon, the expense of building and operating the trireme slowed its adoption. The construction of first-class triremes required not only skilled shipwrights but also costly materials such as pitch and wax for waterproofing, and fir, which gave lightweight strength to hull and oars. In addition, because each ship required a skilled crew of two hundred, the operational cost of a fleet of triremes exceeded the means of all but the wealthiest states. Thus, in addition to Necho in Egypt, early trireme users included commercially prominent city-states such as Corinth in Greece and Sidon in Phoenicia, and the powerful Greek tyrant Polycrates of Samos, who replaced his fleet of one hundred pentekontors with one of triremes.

In the late sixth century, the adoption of the trireme by the superpower of the day, Persia, guaranteed its predominance and made it the warship of choice for those Greek states that wished to resist the expansion of the Persian Empire into the Aegean region. Drawing on his Phoenician, Egyptian, and eastern Greek subjects, Xerxes put together a gigantic fleet of twelve hundred triremes for his invasion of Greece in 480 b.c.e., an assault that may well have succeeded except for the Greeks’ historic naval victory at Salamis. Greek triremes were the key to this victory, above all the two hundred ships that Themistocles had convinced the Athenians to build using the proceeds of a fortunate silver strike. Following the defeat of Xerxes, triremes and the tactics associated with them dominated Greek naval warfare for more than a century.

Although it was used sometimes in what Thucydides called the “old-fashioned manner,” with marines in boarding attacks, the trireme excelled when the ship itself was used as a ramming weapon. Rival fleets of triremes typically faced each other in line abreast, and the defender attempted to avoid presenting vulnerable sides and sterns to the rams of the enemy. A drastically inferior force might form a defensive circle with bows facing outward. The attacking force sought to achieve diekplous, a breakthrough by a squadron of ships in line, or periplous, a flanking maneuver, either of which permitted ramming the enemy broadside. Once a ship had been holed, the attacker quickly disengaged to avoid a counterattack and resumed the offensive. Given these tactics, the advantage normally went to the swifter and more agile ships, a status determined partly by their design but also by how long the ships had been in the water and the expertness of their crews. In the victory at Salamis, for example, the normally slower Greek triremes probably had the advantage of speed, because their ships were drier and their crews more rested than those of the Persian force. The Athenians were renowned for the speed of their triremes, and their mastery of hit-and-run ramming tactics regularly let them defeat larger, less-skilled forces. In a famous encounter early in the Peloponnesian War, for example, a twenty-ship Athenian squadron commanded by the expert Phormion twice defeated larger Peloponnesian fleets.


As long as ramming tactics prevailed and skilled oarsmen were available, the trireme dominated ancient naval warfare. Beginning in the fourth century, however, a shortage of skilled crewmen encouraged the development of new rowing configurations that made use of less-skilled personnel. By manning each oar with a pair of rowers, only one of whom needed real expertise, it was possible to produce a two-banked “four,” which required one third fewer expert rowers but maintained the sleekness and speed of the trireme. The first “four” is attributed to the Phoenicians at Carthage. By 323 b.c.e., the Athenians planned a new fleet based primarily on “fours” rather than triremes. The use of rowers in teams of three or more produced ships of broader beam, which were slower and less agile than the trireme, but by the end of the fourth century new tactics were beginning to favor larger, more stable ships. By using various combinations of rowers in gangs of three, four, or more per oar, Hellenistic navies introduced much larger warships, from “fives” up to huge “sixteens,” that provided stable firing platforms for catapults and excellent protection to their large crews of rowers and marines. Aptly suited to naval combat in the “old-fashioned manner,” these vessels marked a return to tactics completely alien to the trireme and relegated it to an ancillary role in Hellenistic warfare.

Further Reading
  • citation-type="booksimple"

    xlink:type="simple">Casson, Lionel. Ships and Seamanship in the Ancient World. 1971. Reprint. Baltimore, Md.: The Johns Hopkins University Press, 1995. This study offers a general overview of ancient seafaring and includes a chapter on the trireme.
  • citation-type="booksimple"

    xlink:type="simple">Gabrielsen, Vincent. Financing the Athenian Fleet: Public Taxation and Social Relations. Baltimore, Md.: The Johns Hopkins University Press, 1994. Provides background on the financial aspects of maintaining a fleet in ancient Greece.
  • citation-type="booksimple"

    xlink:type="simple">Morrison, John S., J. F. Coates, and N. B. Rankov. The Athenian Trireme: The History and Reconstruction of an Ancient Greek Warship. 2d ed. New York: Cambridge University Press, 2000. The most important volume on this subject, this study analyzes all aspects of the trireme’s history and incorporates knowledge gained from the modern replica.
  • citation-type="booksimple"

    xlink:type="simple">Shaw, Timothy, ed. The Trireme Project: Operational Experience 1987-90, Lessons Learnt. Oxford, England: Oxbow Books, 1993. This anthology contains essays, some quite technical, on many aspects of the construction and operation of the full-scale replica.
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