Between 489 and 480 BC Athens expanded their fleet from 40 to 200 triremes, funded by a new silver mine discovered near Laurion. This investment by the city, and the maintenance of each ship funded by wealthy citizens, would make Athens the dominant naval power in the Mediterranean for much of the next century.
The trireme was a fast and maneuverable ship that earned its name from its three rows of oarsmen. It was a natural progression from bireme, which held two rows of oarsmen.
The trireme, however, wasn't simply a bigger is better version of the bireme. The steep angle between each of the three tiers of oarsmen allowed them to dramatically increase the ratio of rowing power to ship size. A trireme held 170 citizen oarsmen (as opposed to slaves, used in some other contemporary navies), 31 in the top file, and 27 each in the middle and lower files. They sat one per oar, spaced approximately 2 cubits (2 feet, 9 inches) apart. The oars varied in length from 13 feet to 13 feet and 8 inches, depending on their placement at the ends or in the middle of the ship. As Aristophanes pointed out, the advantage of sitting in a higher tier wasn't just a better view; there was no doubt an unpleasant odor in the bowels of the ship on long voyages.
At sea, with its square sail unfurled to compliment the rowers, a trireme could maintain a speed of approximately 7.5 knots. However, when stripped down for battle the sail was left ashore, and the highly trained oarsmen supplied all of the propulsion and maneuverability that made these ships deadly. Sitting just beneath the waterline was the key to the trireme's military purpose: a bronze battering ram weighing over 400 lbs. Under full oar the trireme was a waterborne missile, capable of inflicting fantastic damage on its target, in some cases even shearing another ship in half.
The trireme's decisive role in naval warfare was never more clear than during the Persian invasion under Xerxes, a war recently bought to pop culture in the movie 300, which tells the story of the Spartan stand at Thermopylae. It's an incredible story, but hardly complete. While the Spartans and their allies were locked in tight phalanx, dying to the last man at Themopylae to hold Xerxes' land forces as long as they could, a Greek navy -- composed primarily of Athenians -- was outnumbered almost 3 to 1 in the Battle of Artemisium.
In 480 BC, after what historians have suggested may have been a misunderstanding of the Persian fleet's intent, the Greeks met the Persians in a 3 day battle, sinking approximately 200 Persian ships but losing around 100 Greek ships in the process. The naval stand at Artemisium required the Spartans to hold Thermopylae as well, so on hearing that the Spartans had been crushed, and faced with losses the smaller Greek fleet could not afford, their Athenian commander, Themistocles, ordered a retreat to Salamis Island.
Faced with Persian encroachment on land, and unable to fully barricade Persian troop movement without securing the coast to prevent Persian movement by ship the Greek navy had to take action. Rather than engage in a defensive blockade, Themistocles convinced the Greeks to engage in a bold offense. Drawing from the lessons learned at Artemisium, he recognized that close-packed naval warfare favored the quick and maneuverable Greek ships.
Once again the Greek fleet of just under 400 ships faced overwhelming odds. Although Herodotus puts the number of Persian ships at just over 1,200 some modern historians argue that based on attrition in previous battles and to shipwrecks in storms the Persian fleet most likely consisted of no more than 600-800 ships. Even assuming the lowest estimate, the Persians held a decided advantage in numbers.
The specifics of the battle remain vague; no observer or participant had a complete view, and representatives of various city-states accounts of the battle elevated their own contribution above those of others. By some accounts there was initial confusion on both sides about the actions and intent of their opponents.
The Persian navy, cramped once it entered the narrow straits between Salamis and the mainland, had been led to believe that the Greek alliance and her navy was disintegrating in confusion. Instead they found the navy lined up and fully prepared for battle. The Persians had smashed through the Spartans at Thermopylae, forced a retreat at Artemisium, conquered Boeotia and Attica. The Persian advance across Greece had forced the evacuation of Athens. There was nowhere left to retreat, the invading Persians had to be stopped, and they had to be stopped at Salamis.
According to Aeschylus, who fought at Salamis, the Persians were greeted by the sound of the navy, under their Athenian commander, singing this battle hymn:
Forward, sons of the Greeks, Liberate the fatherland, Liberate your children, your women, The altars of the gods of your fathers And the graves of your forebears: Now is the fight for everything.
By some accounts the Greek line began to back up, whether seeking to gain an optimal position or simply buying time waiting for the morning winds is unclear. What is clear is the decisive victory the Persians had sought instead went to the Greeks.
The advance of the Greek navy drove the first line of Persians back into their own reinforcing ranks, sinking ships and boarding those that remained afloat with hoplite infantry. The Persian admiral, Ariabignes (Xerxes own brother), was killed early in the day, adding to the confusion. Before the day was done the Persian line had been split in two, and over 200 of their ships had been sunk. Persian casualties were extremely heavy, according to Herodotus, because many of the Persians didn't know how to swim.
Although it wasn't until the following year, in 479 BC, that the Persian invasion was fully defeated in the battle of Plataea, the victory at Salamis is widely regarded as a major turning point in the war.
No shipbuilding manuals or documentation survived from ancient Athens or her sister cities in Greece. The trireme, a ship that ruled the Mediterranean, defeated the uncountable armies of Xerxes, and left its mark on naval technology for hundreds of years, seemed destined never to be seen again.
But was it? Historians painstakingly searched through ancient art and literature for information about the specific dimensions and construction of the ship that changed the course of naval warfare. In 1985 construction began on the Olympias, a full size, seaworthy trireme, and in 1987 the Olympias became the first trireme to sail in approximately 2,000 years. With a crew of 170 inexperienced volunteers she achieved a speed of 9 knots, and executed 180 degree turns in under a minute. The legendary speed and agility of the Athenian warship was proven to be no exaggeration.
The domination of the trireme wasn't a coincidence. The Greek navy, particularly the Athenians, had found a near perfect balance of engineering, skilled and proud crewmen, and tactics that capitalized on the ship's advantages.