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Gibraltar is an ideal location in which to study the development of artillery as it retains tangible examples of various important stages.
In Medieval times the main long-range weapon was the bow & arrow. For attacking heavy fortifications they used a catapult to hurl stones at the walls. These catapults were called siege engines or trebuchets. In the 1300s gunpowder or black powder arrived in Europe from China, brought here by the Moors, revolutionising warfare in Europe with the advent of the cannon. The first recorded use of a cannon in Europe was to defend the city of Algeciras during the siege of 1343-44.
Early cannon were made with long metal staves heated and hammered together with hoops then added on top to reinforce them. This was exactly the same method used to make wine barrels and that’s why this part of a gun is still called the barrel today.
Early on there was lots of experimentation with different ideas such as loading from the back end, called the breech, and using different materials, even including a Swedish design for a leather cannon, but from the 1500s to the mid-1800s most cannon conformed to a fairly standard design which changed little.
Metal, usually iron or bronze, was heated until molten, then poured into a sand mould. The mould contained an iron bar, covered in clay, called a Newel. This created a smooth inner barrel, called the bore and these guns were loaded from the front end, or muzzle. Two round bars sticking out of the barrel at about the balance point were called trunnions and were used to mount the cannon on a carriage. They allowed the barrel to pivot up and down. The rear end had a rounded dome called the cascabel.
To load the cannon, a quantity of black powder was ladled into the barrel and rammed in, followed by a ‘wadding’ of cloth or straw. Then a solid iron cannonball of slightly less diameter than the bore was rammed in, followed by more wadding. At the back of the bore was a hollow tube called the touch hole which went to the outside of the barrel. This was filled with fine-grained powder. To fire the cannon, a smouldering piece of thick string, called a slow match, was placed on the touch hole. This burnt the fine powder, which then exploded the powder in the bore, sending the cannonball shooting forward to its target. Before re-loading, the barrel had to be cleaned. A long rod with the end shaped like a corkscrew was used to scrape away solidified powder residue, then a wet swab was used to clean out any embers that remained. A practiced crew could fire a shot every two minutes.
Cannon were known by the weight of the ball, or ‘shot’ which they fired, in pounds. Early guns were as little as only three or four pounders, but gradually they got bigger. 18, 24 and 32 pounders were common sizes. The last and biggest were 64 and 68 pounders. With the increase in size, so the maximum range increased. Minimum range was when the barrel was exactly horizontal, or ‘point-blank’, but if the barrel was elevated, the range increased. An elevation of only five degrees could increase the range four-fold. Typical ranges are for a 9 pounder(pdr) – 1.2km, 24pdr – 1.8km and 32pdr – 2.4km. The barrel was set to the required elevation with a wooden wedge called a quoin placed under the cascabel. As the enemy got closer, the quoin was hammered in, pivoting the muzzle down and reducing the range. Later Victorian guns used a screw system instead.
Although cannon changed little, the carriages they were mounted on did. For field use they were originally static and could only be moved by placing them on sturdy wagons and hauling them into position with oxen, but by the late 1600s small guns could be mounted on a wheeled limber and the gun moved quickly by horse to where needed on the battlefield – the first truly mobile land artillery.
On board ship, cannon did not need this degree of mobility, so naval carriages had four small wheels used to help aim the gun and ‘run it out’ – push it forward to its firing position after it had recoiled from a previous shot and been cleaned and reloaded. Many naval guns had a heavy metal loop on the cascabel called a pomellion. A wide rope passed through this and was fixed to the hull on both sides, to reduce recoil. To help running out, ropes with pulleys, called breeching lines, ran from the carriage to the ship’s hull.
Cannon for use in static land defensive positions like Gibraltar were mounted on Garrison Carriages, which were similar to the naval carriages, but here there was a special development. In 1782, Lieutenant George Koehler of the Royal Artillery demonstrated the special ‘Depression Carriage’ which he had invented. Because of the need to fire downwards from the north face of the Rock, he adapted a standard garrison carriage to fit on a special platform. This could be raised at the back to allow the cannon to fire down at angles up to 70 degrees (extra wadding was packed in after the cannonball, so it did not roll out prematurely). The carriage could slide on the platform, so when it fired, gravity reduced the upwards recoil and stopped the platform from moving, making the shot more accurate. Additionally, the barrel could be pivoted sideways, so when operated from an embrasure the crew were protected from enemy fire through the narrow aperture whilst they cleaned and re-loaded.
Some specialist types of cannon did emerge. Short, wide-diameter Howitzers and Mortars fired in a high arc. Mortar bombs were unlike solid cannonballs. They were hollow, packed with powder and fitted with a fuse, designed to explode above the enemy. This was particularly devastating when used against troops on open ground.
There were problems with cannon. Because the barrel was slightly wider than the cannonball, there was a slight gap between the two, called ‘windage’ and this had two effects. Firstly, some of the explosive power of the gunpowder escaped past the cannonball, reducing its force, and hence the range of the shot. Secondly, as the cannonball ‘rattled’ out of the barrel, each shot went in a slightly different direction. This poor accuracy meant that many cannon had to be used to increase the chances of hitting the target.
Another major problem was the basic casting process used to make the guns, which made them liable to split or even blow up when fired – this could have fatal consequences for the crew. It has been suggested that Artillerymen were at as much risk of death from their own cannon as from those of the enemy. The solution to this problem would soon be provided by improving technology. The invention of the metal-cutting lathe meant that as from 1739, cannon could be cast in one piece, then bored out ‘from the solid’. The resultant guns were very much stronger and less likely to split. This not only improved safety, but also meant that larger and more powerful guns could be made.
Improvements in engineering and technology during the industrial revolution would bring about the greatest changes in artillery for 300 years, one of which was rifling. Steel became commercially available in the 1850s and a steel tube could have a number of spiral grooves running down its length, called rifling. When used in a barrel, these grooves would spin the projectile, markedly increasing its range and accuracy, making smooth-bore guns obsolete. Some large smooth-bore guns were ground out and had a rifled tube inserted, but new ones, were purpose-built.
Sir William Armstrong was an innovative engineer from Tyneside, who supplied cannon to the military. He had produced breech-loading guns for them, but as problems were envisaged with these, the Admiralty preferred to stick to the existing system and in 1865 adopted his design for a new Rifled Muzzle Loader, or RML. His system was to take a strong central steel tube, then shrink onto it hoops of wrought iron, with the thickest section at the back end of the barrel, where the force of the exploding gunpowder was greatest. These steel and wrought iron guns proved much stronger than the old cast ones and could be made much bigger. The Admiralty produced a large number of these guns, which were classified not by the weight of the projectile, but by the diameter of the bore. They were primarily intended to be mounted on ships, but as they were also ideal for coastal defence, many were sent to Gibraltar.
Because the RMLs were more powerful, more accurate and with a longer range than the old smooth-bores, Gibraltar’s bastions had to be adapted to take them, with many small guns being replaced by a few large ones. Batteries, like Parson’s Lodge, were fitted with two or three 10-inch, 18-ton guns, protected on the sides by thick stone walls and in front by the laminated iron and teak shield invented in Gibraltar and now known everywhere as the ‘Gibraltar Shield’. Other places, like Harding’s Battery at Europa Point, housed a single 12.5-inch, 38-ton gun in a round, open-topped, enclosure called a Barbette. The wheeled carriage sat on a platform which for the larger guns was fitted with a water tank and hydraulic buffer to absorb the recoil. The platform could traverse (move left and right) on wheels that ran on a curved iron track called a racer. King’s Bastion housed four 10-inch RMLs, with a single 12.5-inch in the middle.
The largest RML produced by William Armstrong was a 17.72-inch, 100-ton gun, first made in 1870. The Admiralty rejected it, until the Italian Navy bought four to mount on their ‘Duilio’ class battleships. This made British naval bases in the Mediterranean vulnerable, so the Admiralty purchased four, two for Malta and two for Gibraltar. The one at Lord Napier of Magdala Battery still sits on its mountings today.
As the guns themselves changed dramatically, so did the ammunition they fired. Round shot gave way to longer, more aerodynamic shells. To engage the rifling, to spin the shell and make it more accurate, early shells were fitted with studs. Later ‘studless’ shells had a shaped, bronze ‘gas check’ ring at the base which fitted the grooves and which expanded when the powder exploded, eliminating windage and increasing range. Shells could be ‘Common’, containing ordinary explosive, ‘Shrapnel’, containing metal bullets, or ‘Palliser’, depending on the target. These were detonated by timed or impact-operated fuses.
During the late 1800s, wooden-hulled ships were being replaced by armour-plated vessels, which were immune to a standard shell. Major William Palliser developed a way of rapidly cooling the cast pointed nose of the shell, making it so hard that it would penetrate the thickest armour of the time. The ‘Palliser’, or armour-piercing shell was born.
Powder was no longer loose-ladled, but pre-packed in silk bags, which after being rammed in, had to be pricked through the touch-hole to expose the powder. Silk was used as it almost all burnt away, leaving little residue. Instead of loose powder and a slow match, the charge was ignited by a friction tube inserted in the touch-hole. When a rope lanyard on the tube was pulled, it operated like striking a match on a matchbox. Later RMLs used a wire heated by electricity to achieve ignition. In a 10-inch RML, a charge-bag of 70 pounds (32kg) of powder could fire a Palliser shell weighing 400 pounds (181kg) over four kilometres. Loading was still done by hand and took around three minutes. The development of optical sights at this time helped to improve accuracy. In the 1870s and 1880s these large RMLs were the ultimate weapon, but by the 1890s they, like the old smooth-bores they replaced, also became obsolete. They never fired a shot in anger in Gibraltar.
Although the Admiralty had abandoned the idea of breech-loading (BL), other nations continued to develop the technology, making it safe. The year 1890 saw the first of the new large breech-loading (BL) guns enter service on the Rock. As they were loaded from the rear, the charge could be placed in a case attached to the shell to make it one unit like the ‘bullet’ we are familiar with today. This made hydraulically-assisted loading, and hence firing, much faster, so these guns were designated Quick-Firing (QF). Another improvement was to replace gunpowder with cordite. Loose powder ignited all in one go, which meant that the shell was slowing down even before it left the barrel. Spaghetti-like sticks of cordite took more time to burn, so with a longer barrel the accelerating force was greater and the range much longer. A small hollow cylinder, called a percussion cap, was fitted to the base of the case. It was filled with a shock-sensitive explosive and, when struck by a ‘firing pin’, ignited the cordite and fired the gun.
For large targets, the replacement for the RMLs was the 9.2-inch BL gun and a line of 14 of these was installed at the south end and along the ridge of the Rock. With a range of over 25 km, they could cover across to Africa, totally dominating the area. Able to fire illuminating shells and depth-charges, as well as armour-piercing explosive shells, the result was that Britain controlled passage through the Strait all through the First and Second World Wars. These guns were still being operated by the Gibraltar Regiment in the 1970s. For smaller medium-range targets a 6-inch BL was adopted (Devil’s Gap Battery has two examples) and for close-range a 12-pounder. This was Britain’s standard coastal defence armament for over 50 years.
The Second World War (WWII) saw the introduction of the Ordnance 6 pounder-QF gun. This was designed primarily as a mobile anti-tank weapon, but also proved ideal for static defence against landing craft, which is why two of these are found at Parson’s Lodge.
A new feature of 20th Century warfare was the advent of aircraft attacks, against which a quick-firing capability and automatic re-loading were essential. During the First World Wart (WWI) the British developed a 3-inch heavy anti-aircraft gun, joined in WWII by a larger 3.7-inch version. Many were mounted in Gibraltar and one still sits next to the 100-ton gun. Lighter anti-aircraft defence was provided by the Bofors 40mm gun. Again, many were sited here to defend the Rock, including one which sat on the roof of Parson’s Lodge. Its mounting post is still there today.