The great 'Age of Sail' could technically be said to have existed in the 250 year period between about 1600 to 1850, although obviously sailing vessels had been used across the world for thousands of years previously. However, it was about this time that sea power became a vital role in the aggressive expansion plans of the major powers of the day, mainly the nations of Europe.
The main change over times past, aside from the sophistication and robustness of the ships, was the sheer quantity of vessels plying the seas, largely due to improved navigation techniques, and also their prominence as tools of war. Prior to this time vessels of war were relatively small, and generally operated independently or in small groups. The larger sea battles of antiquity, such as the clash between Greek and Persian fleets in Salamis Bay, were anomalous, with the bulk of historical conflicts being restricted to land. Similarly, where sea power played a major role in land engagements, such as the Norman amphibious invasion of England in 1066, again the role of ships was limited to transport, reconnaissance or support.
The Age of Sail Dawns
The major seafaring powers, such as England, Spain and France, began an extensive programme of exploration around the 15th Century as the 'New World' of the Americas opened up. Minor clashes over trade routes and territory began to occur with growing frequency, as well as a trend for state-sponsored privateering in the treasure-rich Caribbean (provided you restricted your robbing to the enemy, many pirates were encouraged by the governments and monarchies of the day...)
It was the Spanish Armada of 1588 that arguably began the trend for large-scale sea battles, with the Spanish accumulating an unprecedented number of ships in the same place in order to mount an invasion of England. King Philip II intended to forcibly convert Protestant England to the Church of Rome, and the Armada was, it was believed, an invincible means of doing so. While popular history records the British triumph over a numerically superior force as a matter of will and courage, they were also undoubtedly aided by the Spanish encountering bad weather, bad luck and bad seamanship. However, suddenly supremacy at sea became a vital issue, and it was here that Britain, with her 'Heart of Oak' managed to excel. In an era without prefabrication, the sheer variety of warships produced was staggering, with many often being completely unique. However,all followed a simple principle when it came to combat. Termed 'Men of War', such ships were rated by the number of guns. Heavily armed, they were impressive but slow and difficult to handle.
Tactics and weapons in the Age of Sail
The tactics of engagements were simple in concept, difficult in practice. Warships would line one deck or more with guns, and the vessel would be turned so that the sides of the ship could rake the target with fire. This was called a broadside, and given that the cannons had a limited arc of fire and that trajectory was affected constantly by the roll of the ship, good gunners were prized by all sides.
The shot used was of varying kinds. Solid slugs of metal could pound through a wooden hull, the kinetic energy sending white hot shards into the crew on the other side. Small canisters of shrapnel could shred sails and masts - and the men in them. Additionally, sails could easily catch fire and rain down burning debris, while the heavy masts could fall and crush anything below. Also, with the firestorms created in battle pulling the air in every direction as they consumed oxygen, steering a sailing ship under such conditions was problematic at best.
The guns of the time lacked rifling to stabilise rounds (which were often just rough spheres anyway), so firing was slightly haphazard and munitions that spread out like giant shotgun blasts were often favoured. As such, most engagements were fought at relatively short range - so much so that often grapples would be used to board an enemy ship if the opportunity arose. By the time the Napoleonic wars began in the late 18th Century, with most powers having many far-flung colonies that required frequent supply and defence, sea battles were as common and vital as those fought on land.
Grand fleets of giant vessels emerged, some with three decks of guns, the amounts of cannons carried numbering into the hundreds. Minor engagements and scouting duties were left to smaller ships, and generally the more important conflicts saw dozens of mighty ships converging to pour searing shot on one another from mighty broadsides, until either the hulls or the crews of the opposing ships could take no more. The Battle of Trafalgar in 1805 will always remain the defining moment in this style of sea warfare, but from across the Atlantic a revolution in ship design was dawning.
The Coming of the Ironclads
While masted ships that relied on broadside tactics remained in service until the end of the 19th century, the American Civil War (1861-1865) demonstrated some innovations that the seafaring powers of the world could ill afford to ignore. When the Union vessel USS Monitor engaged the Confederate ship CSS Virginia on March 22 1862 at Hampton Roads on the Elizabeth River, the battle was a stalemate. Both ships used iron armour on their hulls that effectively resisted cannon fire, and they also brought several other innovations to light. Both used steam engines, removing the need for vulnerable masts and rigging - and wind! Monitor's largely submerged hull extended only a few inches above the waterline, making her a tough target to hit, and while she only had two guns, they were encased in a turret that could traverse almost a full circle, meaning that no longer did a ship have to maneuver its full hull to aim. Virginia, formerly USS Merrimac, a conventional masted ship captured early in the war, retained broadsides and a high hull, but had her armour angled inwards so that shots were inclined to skip off it rather than impact.
The End of the Age of Sail
There was a period in the late Victorian era when the arrogant, inflexible admiralties of the globe tried to resist such innovations, and vessels such as the HMS Warrior, launched in 1860, were little more than overlarge sailing ships with a layer of iron armour and engines. Even after Hampton Roads this philosophy continued for several decades. However, by World War I most warships were of the 'Dreadnought' type - mastless, all metal steamers with heavy guns fitted into rotating turrets. This said, the tactics of the Age of Sail were slower to disappear than its ships, with large fleet actions like Dogger Bank still the approved way of fighting war at sea. It would be World War II before engagements by entire fleets became uncommon, with the advent of efficient submarines and anti-shipping aircraft ready to take advantage of the target opportunities a large body of vessels could present.