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Red hot shot and explosive shell in the French Navy

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  • Red hot shot and explosive shell in the French Navy

    The problem faced by the French at the end of the eighteenth century was the superiority of the Royal Navy in spite of the more advanced design of French warships. One key factor in this was that the Royal Navy’s gunnery was so much better; in general this was superior in accuracy, rate of fire and weight of broadside. The much maligned British impressment system had resulted in a circular flow of trained and experienced sailors between the mercantile and fighting navies so that there was a growing pool of British seamen who had been trained to man the guns. The French navy suffered a continual loss of trained gunners as the army was always hungry to man its artillery units and regarded the navy as a form of gunner mine. The Revolution itself had purged many naval officers with the necessary experience to organise their fleet’s gunnery. Britain had a much stronger industrial base and was better able to equip the Royal Navy with heavy guns. French ships continued to be mainly equipped with 24 pounders where many British ships had been fitted with 32 pounders. There was little chance that the imbalance could be effectively reduced and so a new strategy was sought. If the French gunners could not hit their opponents as often or with as great a weight of metal then they would be provided with ‘secret’ weapons to increase the effect when they did succeed in scoring hits.

    The first solution adopted was the use of red hot shot fired from ships. Red hot shot itself was nothing new having been introduced by the Poles in the late 16th century. Round shot heated in a furnace could be fired from cannon, provided a sufficiently thick wad was interposed between the shot and the gunpowder charge. A red hot shot holds a significant amount of heat energy and if embedded in an inflammable substance such as wood will cause a fire that is very difficult to extinguish even with copious amounts of water. This made it very dangerous to the wooden ships of the day so that whilst it was occasionally used in siege warfare its main employment had been in coastal batteries. Everyone condemned the use of red hot shot and everyone used it. It was, for example, instrumental in defending Gibraltar against the Spanish and French naval forces during the American War of Independence.

    The combination of heated shot, furnaces and gunpowder in close proximity could be dangerous even when used on a stable platform such as a stone built fortified battery. Rigorous procedures were developed to control the loading of powder into the guns, the carriage of the heated shot from the furnace and its loading into the cannon. The purpose of these was to ensure that powder and red hot shot did not make contact with each other. Although a fictional account, C.S.Forester’s novel “Lieutenant Hornblower” provides an excellent description of the rigorous control needed when using heated shot. Nevertheless accidents did happen. In 1806 the British frigates Anson and Arethusa had cornered and taken the Spanish frigate Pomona near Moro Castle in Cuba. They then came under fire from the castle, which was firing red hot shot from 32 pounder guns. This started a fire in Arethusa that was soon put out but shortly afterwards a terrific explosion occurred in the fortress and all firing stopped. One has to assume that careless handling of the red hot shot had resulted in an explosion in the magazine. One can imagine a cannon ball, glowing red, being dropped from its special carrying cradle and rolling back into the entrance to the magazine.

    If using heated shot in the stable and relatively fireproof environment of a stone fortress was hazardous just imagine conditions on board a wooden man of war, built of combustible material, moving with the motion of wind and sea and with enemy cannon balls thudding into and through the hull. In a Royal Navy ship all fires (such as the galley fire) were extinguished before going into action. This was to avoid the risk of a conflagration due to an enemy cannon shot hitting the fireplace. In a French ship using red hot shot going into action would mean deliberately lighting a furnace to heat the shot. Just remember that red hot shot is intended to set wooden ships ablaze and now red hot shot would have to be handled, under fire, on board a heaving and tossing wooden ship. Despite this in 1794 four French ships of the line engaged in the battle known as the Glorious 1st of June (the French call it the 3rd battle of Ushant but then they lost) were equipped with furnaces for heating shot. On the third day of the battle the French admiral (Joyeuse) made the signal to heat the furnaces for red hot shot. HMS Royal Sovereign and HMS Orion were both hit by heated shot but sustained no significant damage. The battle ended with the French fleet loosing seven ships of the line (one sunk). Superior British gunnery had played a major part in the Royal Navy’s victory.
    So the ‘secret’ weapon had failed to deliver. The British fleet had not been set ablaze. Details of the set up for firing heated shot from ships are scarce (kept deliberately so by the French revolutionary government for many countries at the time considered this a breach of the rules of warfare – a war crime if such a term had then been extant). However an eyewitness account from a seaman on HMS Orion reveals details that shed a light on this (and on the disaster that was to follow).

    “she (a French 80 gun ship) contrived to send a red hot shot into the Captain's cabin where I am quartered, which kept rolling about and burning everybody, when gallant Mears, our first lieutenant, took it up in his speaking trumpet and threw it overboard.”

    It is obvious that this shot did not come from the heavy 32 or 24 pounder guns that would make up the main French broadside, given the size of the metal speaking trumpet used by Royal Navy officers it could be have been a 12 pounder shot at the largest and more probably a 9 pounder. At this size it would not retain sufficient heat energy to start a fire immediately. This makes sense when one considers the large amount of wood or charcoal needed to bring iron to red heat. Ships of the time often had difficulties carrying enough firewood for the basic task of boiling the crew’s food (to remove the salt) and next to shortage of water lack of galley fuel was the main reason for seeking port for replenishments. It would have not been practical to carry enough to heat up whole broadsides of large shot (and in any case the furnaces would have had to be very large indeed). So a smaller furnace serving the lesser guns must have been used. It would need to be located fairly close to them to avoid carrying the red hot cannon balls up and down ladders. On French ships of the line these guns were mainly situated on the quarterdeck, at the poop and above the captain’s cabin – a point whose significance will become apparent.

    Despite this lack of success the French navy continued to use red hot shot. After a successful action in 1795 by the Royal Navy in the Mediterranean leading to the capture of two French ships of the line it was said;

    “The Ca Ira and Censeur probably defended themselves with more obstinacy in this action, from a persuasion that, if they struck, no quarter would be given; because they had fired red hot shot.”

    As we shall see the French also used heated shot at the Battle of the Nile.

    Although they persisted with heated shot the French sought to introduce a potentially more deadly weapon – explosive shell used in broadsides. Explosive shell had been in use for centuries both on land and sea but only fired by very particular types of gun and from highly specialised ships. The basic explosive shell consisted of a hollow iron ball packed with gunpowder into which had been inserted a fuse. Early explosive shell was dangerous to use, far more so than modern munitions. It was also far less damaging to the target than current shells (although if you were standing beside one when it went off you wouldn’t notice the difference). The problems arose from the lack of a contact fuse to explode the shell on impact, the general inaccuracy of fuses depending on burning powder, the susceptibility to sparks and flame of a gunpowder based projectile and the relatively low explosive yield of gun powder. An 5 inch diameter howitzer shell of the 18th Century probably had less explosive power than a modern hand grenade. Being restricted to round projectiles (an elongated modern shell shape would tumble if fired from a smooth bore greatly reducing range and eliminating any hope of accuracy) also constrained the weight of shell that could be fired from a particular calibre gun. For example if the British 17 pounder anti tank gun of World War two had be constrained to fire only round shot it would have had to have been a 4 pounder.

    In 1788 one Samuel Bentham was in foreign service (as many senior British naval officers were in time of peace). He was in command of Russian naval operations in the Black Sea when Russia and Turkey were involved in yet another of their innumerable wars. The Russian naval forces were greatly outnumbered by the Turks. Bentham equipped a flotilla of small vessels (gun boats and the like) with shell firing howitzers and mortars, cornered the local Turkish fleet in the shallow Sea of Azov (near the Crimea) and burnt it to the water. This success caused naval authorities in many countries to reconsider the use of shell firing weapons for ship to ship combat. In Britain the conclusion was that the safe use of shell at sea required very strict and specialised processes that could not be adhered to on board generalised warships and the risks out weighed the benefits. Shell on bombs was acceptable but not on ships of the line. The French took another view and carried out a series of tests firing shells from heavy cannon at a silhouette of a British man of war. They concluded in 1794 that a supply of shells should be produced for all ships carrying 32 pounder guns. At the same time a naval carriage was developed to allow the deployment of the French army 5 inch howitzer on ships. This weapon had approximately the same calibre as the French 32 pounder and so could use the same shells. Its range when firing horizontally through a gun port would be very short.

    It is not known what the feelings of French naval commanders were about taking large numbers of explosive shell on board their wooden ships but they would have little choice. The French revolutionary government had placed a number of representatives of the Committee for Public Safety in the fleet and it would have been a choice between taking the shells or the guillotine. There is evidence that the shells were not regarded as likely to be very effective. In January 1797 the French ship of the line Droits de l’Homme was being harried by two British frigates, the Amazon and the Indefatigable (under the overall command of Captain Pellew). The Droits de l’Homme fired all of its heavy solid round shot (some 4,000 rounds) before starting to use shell which must have been regarded as a last resort. It certainly caused no causalities on either British ship. It was all in vain as the Droits de l’Homme was forced aground at Hodierne Bay in a raging storm and broke up with the loss of over 1,400 crew and soldiers.

    Shells were found on board the captured Ca Ira and Censeur as was a quantity of a special preparation that became liquid when it was ignited, and the use of water would not extinguish its flames. This was carefully concealed (possibly as paint or oil) as its use would definitely be regarded as a major breach of the rules of war. What was not known to the British at the time was that the French were using two different types of shell, one the conventional explosive missile and the other an incendiary device (possibly filled with the above preparation) that once lit would continue to burn even under water exuding a black pitchy substance. This second type of shell was visually no different from the common explosive variety and could only be distinguished by particular marks on the casing (which looked solid but was actually an iron skeleton). This type of projectile was regarded as illegal even by the French (Napoleon complained to the British when Royal Navy gun boats fired shell captured from the French fleet into his camp at Alexandria and some turned out to be incendiary).

    At least two of the French ships of the line at the Battle of the Nile were equipped with both types of shell. The Spartiate was captured with a quantity on board and fragments of both were found in the hull of HMS Bellerophon after she had exchanged fire with the French flagship L’Orient. It would seem likely that the closeness of the two ships meant that the shells had shattered against the Bellerophon before the fuse had had time to ignite them. There appears to have been only one casualty caused by shell in the British fleet, a powder monkey in HMS Goliath was killed by blast.

    The French were less fortunate. At nine a clock that evening fire broke out on L’Orient at or near the poop, possibly in the Captain’s cabin. It was a peculiarly fierce fire and within minutes had burned its way through to the decks below. At some point inflammable liquid became involved. This has sometimes been thought to have been carelessly stowed paint and oil but could also have been either the preparation described above or incendiary shells. Certainly burning liquid was observed to be flowing out of L’Orient’s gun ports and down the ship’s side. One would not have thought that that much paint would have been on deck, especially before a battle, but if incendiary shells had been placed by the guns for loading this would be a credible source. The fire was particularly fierce and rapid and within an hour of it starting the ship blew up in a tremendous explosion. Subsequent archaeological investigation has revealed there were in fact two explosions one being the magazine and the other likely to have been the store of explosive shells but which initiated the other remains a moot point. The explosion of the French flagship effectively signalled the end of the main battle. Four of the French battleships had been forced to drop out of line to avoid the risk of the fire and the explosion and had gone aground (three were captured and the fourth set on fire by her crew). When the L’Orient exploded she took with her Napoleon’s war chest and therefore his means of financing his Egyptian campaign which was ultimately doomed.

    It has been suggested by some present that the fire was started by the accidental ignition of one of the incendiary shells in the Captain’s cabin. This would certainly explain why the initial fire was so fierce and difficult to extinguish. The captain’s cabin was a location traditionally used on ships for setting fuses for shells. If one adds to this that red hot shot was heated and fired from the same vicinity and one that British round shot would have been crashing around then a fire seems almost inevitable. Certainly there should be no surprise that a wooden ship carrying a variety of devices specifically intended to set wooden ships on fire should itself burn fiercely.

    After the Nile the French appetite for outré weapons seems to have waned, certainly there is no evidence of shell or heated shot being used at Trafalgar. The Revolution was over and Napoleon was in control. He was no enthusiast for new military technologies (for example he disbanded the French army balloon corps and forbade the adoption of the rifle by his light infantry). In any case the technology was not yet sufficiently advanced to make the use of shell from naval guns sufficiently dangerous to the enemy to out weigh the risks to the user. The standard naval cannon was not a suitable weapon for shell (its calibre was too small to take a worthwhile sized shell) and fuses were too primitive to guarantee an explosion at the right moment (they could even be put out if the standard technique of bouncing shot off the sea into the hull were used). Red hot shot on board ship was just plain stupid.

    However it would seem that the French were not the only navy of the period to have considered the use of shell firing guns at sea. In 1811 the Venetian navy’s frigate Corona was taken after a spirited defence against two British frigates. One of these, HMS Active, took the Corona in tow as most of the latter’s rigging was disabled. For some reason the Corona took fire. It was known that the Corona contained a significant number of shells already primed (fused). The Active had to cast off the tow, a large number of the Corona’s crew leapt overboard and attempted to swim to the Active but many drowned. The Active’s prize crew was able to extinguish the fire and avoid an explosion. This little incident says much about the hazards of carrying gunpowder shells in wooden warships.
    Last edited by MarkV; 16 Dec 15, 05:24.
    Human history becomes more and more a race between education and catastrophe (H G Wells)
    Mit der Dummheit kaempfen Goetter selbst vergebens (Friedrich von Schiller)

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