Boats and canoes were probably used in prehistory to transport fighters and for close combat. However, for the first true warships we need to look to the maritime cultures of the Mediterranean and Middle East. The Phoenician culture of the eastern and southern Mediterranean coasts was especially known for its seagoing skill and shipbuilding, and is sometimes credited with the earliest warships. The truth is probably a bit more complicated. As ships became larger and larger, they would have been used increasingly in warfare as they became more valuable prizes to attack. And larger boats were commonly used in the second millennium BC for carrying out violent raids on other areas of the coast (a piratical activity that the later Greek historian Thucydides described as having been widespread and virtually without stigma in the ancient period.) This made it increasingly crucial to work out forms of defence as well as offence on the seas.
The most commonly used ships for warfare were galleys, powered by rowers. Speed was of the essence, as the main military tactics relied on outmanoeuvring your opponent. The technical names for galleys referred to the number of oars (or the number of banks of rowers) that powered them. Early Greek galleys with a single bank of thirty oars are known as triaconters, for instance, while any single-banked galley can be referred to as a monoreme, a double-banked one as a bireme, and a triple-banked one as a trireme. The banks were necessary to create more powerful vessels, because ships with room for more than about thirty rowers per side were too large for nimble manoeuvres.
The earliest warfare involved attempting to board your opponents’ vessel and defeating them in combat. However, sometime early on in the first millennium BC, things became more complicated with the invention of the ram. A projecting beam at the base of the bow of the ship was covered in metal, and could be used to punch a significant hole in the enemy’s craft. Ships of this ilk were certainly being used by the Phoenicians by about 750 BC.
The development of artillery such as catapults, from the fourth century BC onwards, once again transformed the nature of battleships. Rather than ram an opponent face on, the galleys would attempt to take up a position from which they could do most damage with their long-range barrage, and the ship with a greater range of weaponry held a crucial advantage.
The first Punic War in the third century BC was fought between the growing empire of Rome and Carthage –the city-based empire that had grown from its origins as a Phoenician colony. In the early naval exchanges, the Carthaginians had the upper hand. As a result, Rome built a new fleet of warships that were based on a captured Carthaginian quinquereme. Their main modification was the corvus, a spiked platform that could be lowered onto an adjacent enemy ship so that the soldiers could storm across. This allowed the Romans to apply something closer to their land-based military tactics to the remaining battles of the war, and was a factor in their eventual victory. From this point onwards the Romans were the dominant naval power in the Mediterranean and beyond, but it is notable that most of their shipbuilding knowledge was acquired in the first place from the earlier cultures that they had supplanted.