The naval cannon during the age of sail hardly changed for the best part of three centuries. Improvements were made over time, notably more reliable metal casting and better gun tackles, but the basic design barely altered from the 16th to the end of the 18th century. Warships were equipped with long, muzzle-loading guns mounted on a movable carriage. If gunners from the Mary Rose, which sank in 1545, were transported two and a half centuries through time to the lower deck of the Victory at Trafalgar, they would have had little difficulty recognising the weapons around them. But they might have been puzzled by the carronades mounted on the first rate’s upper deck.
The carronade was the invention of General Robert Melville. He was an artillery officer with a keen interest in scientific improvement. In the 1750s he was investigating how merchant ships might be equipped to protect themselves from attack by privateers or pirates trying to board them. The standard ship’s cannon was a large piece of ordinance that weighed several tons. It required a substantial crew to operate, plenty of room for its vicious recoil and strong ship’s timbers to absorb the stress when it fired, none of which could be provided onboard the majority of civilian ships. Melville decided to redesign the naval cannon to operate within these constraints.
His first step was to reduce the weight of the gun by giving it a much shorter barrel. This drastically reduced its range, but since he saw it mainly being used by a merchant vessel battling an attacker trying to come alongside, this as a minor disadvantage. Giving his weapon such a short barrel produced other benefits. Since it now only needed to throw its ball a limited distance, a third of the usual powder charge of a conventional cannon was required for the same size of ball. A smaller charge required a barrel with thinner walls to contain the blast, saving yet more weight. A reduced charge also produced a gentler recoil, allowing carronade’s to be mounted on a slide, instead of a traditional gun carriage. This meant they took up less space in action. Most of the members of a traditional gun crew were there to run out the gun after loading by heaving their cannon on its wheeled carriage across the deck. A lighter barrel on a slide could be run out by a much fewer sailors.
Melville had the first of his new weapons cast at the Carron Company ironworks in Falkirk, Scotland. He liked to refer to his invention as “smashers”, but they came to be know after the foundry that built them – carronades. They quickly became popular amongst merchant ships, particularly during the American War of Independence, when an over-stretched Royal Navy struggled to protect Britain’s extensive commerce from American and French privateers. This brought the new weapon to the notice of the Admiralty.
At the heart of navy’s interest in the new weapon was a paradox between how traditional naval cannon were designed to be used, and how they were actually used in practise. The traditional ship’s gun, with its long barrel, could throw a ball with reasonable accuracy for up to a mile. But this was an ability that most naval captains barely used. The Royal Navy’s preferred tactic in battle was to engage an opponent at short range, firing quickly into their hull, until the fight was knocked out of them. In these circumstances, how fast a ship could fire its guns, and how heavy the projectile were was much more important than the need to fire accurately at long range.
After initial trials, the Royal Navy began to deploy carronades on the upper decks of their warships, to replace the small guns that were traditionally mounted there. A typical change was made to the 38 gun frigate Diana, for example, when the 9 pounder cannon on her quarterdeck and forecastle were replaced by 32 pdr carronades. These weighed a similar amount, but fired a much larger ball. Early encounters with the enemy quickly showed the benefit of such armament, and by 1800, apart from specialist long-range chase guns, most upper deck cannon had been changed in this way.
One of the French navy’s first encounters with the new weapons came in September 1782. The shock of a single carronade broadside fired at close range by the frigate Rainbow caused a wounded French captain to capitulate and surrender the Hébé, a ship of similar size, but only armed with cannon. After several such encounters with carronade-armed Royal Navy ships, other navies began to develop their own versions of the new weapon. But this took time, and for much of the Revolutionary and Napoleonic Wars they were always more prevalent in the Royal Navy. Carronades helped to give the British a distinct advantage over their opponents in close range encounters. When the Victory passed astern of the Bucentaure at the Battle of Trafalgar, she was able to use the enormous 68pdr carronades on her forecastle to blast canister rounds of over five hundred musket balls sweeping along her opponent’s gun deck. Smashers indeed.
Despite their effectiveness, the age of the carronade was short lived. No sooner had they become widespread then the quickening pace of naval gunnery development made both them and the smooth-bore cannon redundant. The 19th century would be one of steel and industrial progress. New rifled guns firing shells were introduced into the navy, hugely extending the range at which future battles would be fought to far beyond the reach of the Smasher.