The history of the Mediterranean Sea is the history of naval development and armament. Ships played an important part in the Persian Wars of the Greek city states against the Persian Empire as well as in the Peloponnese War between Sparta and Athens and their allies. The Punic Wars of the Romans saw a lot of naval action as well as their in-house squabbles leading up to Octavian taking power as Emperor Augustus.
Triremes were warships where rowers were sitting on three superimposed decks each rowing an oar. They were the common type of warship for all major navies in the Mediterranean by the fifth century BC and they constituted the main armament of the navies during the Persian and the Peloponnese Wars. The name trireme is Latin and is constituted from a number (tri for three) and the word oars (remis); the Greek equivalent is trieres (tri for three) and eres (derived from eressein – to row).
In the second century BC, the Greek historian Polybius claimed that under Dionysius the Elder of Syracuse the first quinquereme (five-oars) was built, while Pliny the Elder points his finger at the Carthaginians for developing the first quadrireme (four-oars). Whatever the case, the fourth century saw an arms race between Cartage, Greek Sicily, and Rome. The new ships were designed to make the most of limited manpower which had been in short supply after the Peloponnese War at least for the Greeks. In the Punic Wars, the quinqereme had become standard issue for all involved.
But the third century BC saw the development of further upgrades; soon hexaremes (six-oars) were being built, to be followed by ever larger polyremes (many-oars). The many Greek kingdoms that came into existence in the wake of Alexander The Great's bid for Empire were especially competitive; flagships in the range of Deceres (ten-oars) became the norm. Winner in the category ‘large’ was Egyptian Pharaoh Ptolemy IV’s tesserakonteres (forty-oars) which was 128 meters long (the Titanic in comparison was 243 meters long); it needed 4,000 rowers and 400 other crew and could transport 3,000 marines. Plutarch noted that the ship looked much like a housing block and was virtually impossible to maneuver.
The ever practical Romans found little sense in building ships larger than septiremes; that is why all types with higher numbers are referred to by Greek names. The Romans found a Decaexeres (16-oars) in the harbor of Pella when they finally annexed the kingdom of Macedonia.
German historian Johann Bernhard Graser made a sketch of a quinquereme during the 19th century in his book De Veterum Re Navali where he seats the five rowers on five decks with an oar to each of them. Such a construction boggles the mind when applied to even larger polyremes. While historians can’t agree on a definite design for any ship type above the trireme, they agree on a maximum of three tiers with rowers seated on them. The conclusion is based on the fact that nothing with a higher build has been found so far.
At Actium, hexaremes were present in great numbers; on the side of Octavian they were the largest ships employed, on the side of Mark Anthony and Cleopatra they were the second smallest. Larger ships while looking impressive lacked maneuverability; the battle of Actium went in favor of Octavian Augustus and Egypt became a Roman province as a consequence. But once the Mediterranean Sea was completely in the hands of the Romans and had become the Mare Nostrum, budget considerations dictated a smaller navy with smaller ships. The knowledge on how to build ships larger than a trireme was lost. As early as the fifth century AD, historians began to ponder on how they could have been constructed and built.