Triremes were ancient war galleys with three rows of oars on each side. They originated with the Phoenicians and are best known from the fleets of Ancient Greece. The trireme was a development of the pentekonter, an ancient warship with a single row of 25 oars on each side. The trireme's staggered seating permitted three row of oarsmen, and an outrigger above the gunwale, projecting laterally beyond it, kept the third row of oars out of the way of the first two. Triremes were the dominant warship in the Mediterranean from the 7th to the 4th century BC.
The date of the introduction of the trireme is uncertain, not only because of ambiguities in the few scattered mentions of triremes by ancient Greek writers, such as Herodotus and Thucydides, but also because the evolutionary development of the ship is not well understood.
According to Thucydides, the trireme was introduced by Ameinocles of Corinth in the late 8th century BC. However, we also know that triremes were not truly effectively used in naval combat until about 525 BC, when according to Herodotus, the ruler Polycrates of Samos was able to contribute 40 triremes to a joint invasion of Egypt. To suppose that no improvements were made to the design of the trireme — as the 40 ships contributed by Polycrates were still relatively primitive — when, in ten years in the early 5th century BC the Athenians were able to make sufficient improvements to the design to ensure their naval ascendancy for 60 years, is something of a stretch of the imagination. Some historians argue, therefore, that the introduction of the trireme did not take place until during the reign of Polycrates of Samos, as he was known to have a fleet of pentekonters at the beginning of his rule, and yet had switched to triremes by 525 BC. This would make the revolution of the design by the Athenians, then, much more plausible.
Add to this the uncertainty over the terminology used in the ancient texts - essentially, there is no guarantee that when the ancient writers used the term "trieres" that they were, in fact, referring to the trireme, and not to just any "warship", and the introduction in the late 8th century BC becomes quite questionable.
However, there are some reinforcements for the suggestion of the earlier introduction. Herodotus mentions that the Egyptian pharaoh Necho (610–595 BC) built triremes on the Nile, for service in the Mediterranean, and in the Red Sea for service in the Indian Ocean. That Pharaoh had close ties with Greece, and especially with Corinth, where it is likely — if the Corinthians had indeed introduced the ship in the late 8th century BC — he acquired the design.
Additionally, there is a fragment of Attica pottery, dated to between 735 and 710 BC, which seems to show a ship with three levels of oarsmen, although the third level is unmanned in the illustration. It is thought that the image represents an early example, or even a prototype, of a trireme, and the unmanned third level is explained, by proponents of the earlier introduction theory, as being quite natural, since the illustration is part of a relief depicting an evacuation, and oarsmen would surely have been in short supply.
It is still not certain which of the two theories is true, and much research is still being done into the questions which surround the introduction of the warship.
Construction and capabilities
Naval combat, during the ascendancy of the trireme, took place mainly by ramming enemy vessels, which would then become unmanoeuverable and subject to capture. In order for this to work well, the boats need to be both fast and maneuverable, which means they ought to have a large number of rowers but still remain as thin and short as possible. Earlier on longboats of increasing length were employed, culminating in the pentekonter, about 35 m long, with 25 oars on each side, which was about the practical size limit for that design. Triremes were a way to construct faster ships without making them too long.
Triremes posed many challenges to the ancient boat-builders. Indeed, until recently, some modern historians doubted that triremes had consisted of three rows of oars, believing this construction beyond the powers of the ancient boat-builders. Some preferred to explain the name by suggesting that triremes had one row of oars with three men on each oar; others suggested that the oarsmen were divided into front, middle, and rear sections.
Triremes had to be made stable (this was two centuries before Archimedes' investigation of the physics of buoyancy and ship stability), which imposed severe limits on their possible height. The lowest row of oarsmen were only half a metre or so above the waterline: their oars stuck out through portholes, with leather gaskets around the portholes to keep the water out. The top row of oars rested on an outrigger that stuck out from the hull by about 60 cm. The rowers were packed very tightly, the lower ones with their noses almost pressed into the bottoms of the men above and in front of them: an uncomfortable position commented on by Aristophanes.
An Athenian trireme was about 35 m long, with a beam of around 5 m. It had a complement of 170 oarsmen, plus a captain, 20 crew, and 10 marines. On each side of the vessel there were 31 thranites (the top row, from thranos, the outrigger) with oars about 4 m long, 27 zygites (the middle row, who sat on the zygos, the crossbeam) with oars about 3 m long and 27 thalamites (the lowest row, who were in the thalamos, the hold) with oars about 2 m long. The captain of a trireme was called a trierarch.
This interpretation of the oar-lengths is disputed by the Trireme Trust, builders of Olympias, the reproduction trireme, as oars of different lengths cannot swing through arcs of the same radius. Olympias was constructed with oars of equal lengths on all three tiers, with the blades nested in line about 6 inches apart. Olympias was successfully rowed in sea trials for multiple years and could exceed 10 knots in full speed rowing; this probably indicates that the Trireme Trust interpretation, based on rowing mechanics, is more plausible.
The blades of the oars came within 30 cm of each other, making the trireme very difficult to row without clashing. The two main ramming tactics were attempting to catch the enemy in the flank, and attempting to glide along side it with the oars pulled in, thereby snapping the other boat's oars and leaving it immobilized. These difficult manoeuvers required a great deal of skill and concentration from the rowers: a single inexpert rower could throw the whole crew off their stroke. Trireme crews had to train hard and long, and were not slaves, but were recruited from the poor but free citizens of the city states, and paid well. Slaves drafted to the galleys in emergencies were freed first. (The resulting manumission of large numbers of slaves after the Persian invasions resulted in significant disruptions to Athenian society). Thus, the crew had a stake in the survival of their city and could be counted on to drill rigorously and to be reliable in combat.
The three rows of oarsmen meant that triremes did not sit especially low in the water, and so were fairly prone to tipping, especially in rough weather. They were equipped with sails, which were taken down before battles, but cramped conditions made them unsuited for long-distance travel unless nearby friendly soil was present to camp upon each night, especially since they did not usually carry a supply of freshwater with them. Sometimes they and other galleys were used to haul cargo, but relatively stable roundships were more often employed.
Since tarring was not known in antiquity, the ships' wood became soaked the longer it stayed in water, and consequently the trireme would ride lower and become much more difficult to propel and manoeuvre. It was therefore essential to keep the ships out of the water whenever possible, so that the wood would dry. This was done by beaching when on expedition, and by hauling the triremes up covered stone ramps, the neosoikoi, when in harbor. Many such neosoikoi (ships' houses) have been found in Piraeus.
According to contemporary writers, triremes were capable of a top speed of 11.5 knots (21 km/hour)for short sprints, of accelerating to full speed in 30 seconds, of turning at top speed within their own length, and of sustained rowing at 7 knots (13 km/hour) for a long time. Thucydides describes an event in 427 BC during the Peloponnesian War in which a trireme was sent from Athens to Mytilene on the island of Lesbos to stop a massacre taking place. The trireme covered the 345 km in a little less than 24 hours; by comparison, a modern ferry makes the journey in 14 hours.
Fleets of triremes employed a variety of tactics. The periplous (Gk., "sailing around") involved outflanking or encircling the enemy so as to attack them in the vulnerable rear; the diekplous (Gk., "Sailing out through") involved a concentrated charge so as to break a hole in the enemy line, allowing galleys to break through and attack the line from behind; and the kuklos (Gk., "circle") was a defensive circle employed against these tactics. In all of these maneuvers, the ability to accelerate faster, row faster, and turn more sharply than one's enemy was very important.
The Greeks defeated the first invasion force at the Battle of Marathon in 490 BC, but realised that pursuing land battles against the more numerous Persians could not hope to win in the long term. When news came that Xerxes was amassing an enormous invasion force in Asia Minor, the Greek cities expanded their navies: in 482 BC the Athenian ruler Themistocles started a programme for the construction of 200 triremes. The project must have been very successful, as 150 Athenian triremes were reported to have seen action in the Battle of Salamis in 480 BC at which Xerxes' second invasion fleet was defeated.
During the Hellenistic period, the trireme was largely supplanted by larger galleys, especially the quinquereme. The numbers did not refer to additional banks of oars, but to the number of rowers per vertical section, with multiple men on an oar. This change was accompanied by an increased reliance on tactics like boarding and using warships as platforms for artillery.
Triremes and smaller vessels continued to be employed, however. Only the poorest states would use them as the core of their navy, but lightened versions were often used as auxiliaries, and were quite effective against the heavier ships thanks to their greater maneuverability. With the rise of Rome, the larger warships became unnecessary, and by Imperial times the fleet had relatively few of them. Instead it was centered around triremes, very similar to those used by the Athenians, and even lighter Liburnians, which had only one or two banks of oars but were different in construction to earlier pentekonters and biremes. The latter would become the basis for the Byzantine dromon and other Medieval galleys.
Ancient writers claim amazing feats for the trireme, and some modern scholars doubted these claims. In 1985–1987 a shipbuilder in Piraeus, financed by Frank Welsh (a Suffolk banker, writer and trireme enthusiast), advised by historians J. S. Morrison and John F. Coates and informed by evidence from underwater archaeology, built a reconstructed Athenian trireme, Olympias.
Crewed by 170 volunteer oarsmen and oarswomen, Olympias in 1988 achieved 9 knots (17 km/h) and was able to turn at top speed in only a length and a half. These results, achieved with inexperienced crew, suggest that the ancient writers were not exaggerating. Additional sea trials took place in 1987, 1990, 1992 and 1994. In 2004 Olympias was used ceremonially to transport the Olympic Flame from the port of Keratsini to the main port of Piraeus as the Olympic Torch Relay entered its final stages in the runup to the 2004 Summer Olympics opening ceremony.
The reconstruction project effectively proved conclusively what had previously been in doubt, that Athenian triremes were arranged with the crew positioned in a staggered arrangement on three levels with one person per oar. This would have made optimum use of the available internal dimensions. However since modern humans are on average approximately 8 inches (20 cm) taller than Ancient Greeks (and the same relative dimensions can be presumed for oarsmen and other athletes), the construction of a craft which followed the precise dimensions of the ancient vessel led to cramped rowing conditions and consequent restrictions on the modern crew's ability to propel the vessel with full efficiency, which perhaps explains why the ancient speed records stand unbroken.
- John F. Coates, The trireme sails again, Scientific American 261(4):68–75, April 1989.
- Vernon Foley and Werner Soedel, Ancient oared warships, Scientific American 244(4):116–129, April 1981.
- Fik Meijer, A History of Seafaring in the Classical World, Croom and Helm, 1986.
- J. S. Morrison, Greek naval tactics in the 5th century BC, International Journal of Nautical Archaeology and Underwater Exploration 3(1):21–26, 1974.
- J. S. Morrison and John F. Coates, Athenian Trireme: the History and Reconstruction of an Ancient Greek Warship, Cambridge University Press, 1986.
- J. S. Morrison and R. T. Williams, Greek Oared Ships: 900–322 BC, Cambridge University Press, 1968.