Gibraltar 100 Ton Gun

Open daily 9:30 – 19:00
Adults £1.00
Children £1.00
Entry is free if you have a FULL PRICE Cable Car ticket

No visit to Gibraltar is complete without a visit to the 100 Ton Gun which is situated at Napier of Magdala Battery. This Victorian supergun is one of only two in the world remaining in such good condition the other being in Malta. This interpretation centre provides an excellent understanding of the manufacture, installation and operation of the gun.

Designed and manufactured in Newcastle-upon-Tyne, by Sir W.C. Armstrong in 1870 and nicknamed ‘The Rock Buster’ – this is the best preserved example of an early ‘Supergun’. Four were originally made and sold to the Italian Navy for mounting on their battleships. The British Government, alarmed that their important Mediterranean bases might be defenceless against long range bombardment from these weapons, commissioned two guns each for Malta and Gibraltar.

The diagram above shows the twin turrets containing two guns each aboard the Italian battleship Duilio.

The 100 Ton Gun Battery was constructed between 23rd December 1878 and 31st March 1884 on the site of the old 2nd and 3rd Rosia Batteries at a cost of £35,717 and named after the governor, Lord Napier of Magdala. Designed during a period of rapid advances in artillery technology, the 100 Ton gun was soon rendered obsolete without ever firing a shot in anger. Nevertheless, the site remained strategically important.

The photo above shows both the scale and labour involved in moving the guns to there positions in Gibraltar. The gun at this battery was unloaded from the ship SS Stanley which landed from England on 10th December 1882. It took 21 days to move the gun 400 yards from the harbour to its final position at the battery.

FACT OR FICTION

In the panorama opposite you can see the relative sizes of a man, shell and muzzel. It is said that during a visit of the Inspector-General of Artillery in 1902 the Gun was prepared to fire 5 rounds at full charge. On the first order to fire, the tube fired but that was all. After further attempts still nothing happened so the misfire drill was carried out but to no avail. At the end of the stipulated 30 minutes wait, the General asked for a volunteer to go down the bore and fasten the shell extractor to the projectile so that the Gun could be unloaded. After a long pause for consideration a small thin soldier stepped forward and volunteered for the task. Stripped to the waist, a rope round him and the extractor ready, he was himself ‘loaded’ into the Gun. A few moments later, to everyone’s relief, he was hauled back safely, having completed his task. The gunner’s reward, though not princely, was immediate, as it is said that he was promoted to the rank of Bombardier that same day. Versions differ over the identity of the volunteer who risked being scattered across the bay, but the most likely candidate to fit inside the barrel was the trumpeter, since he was only a boy. No doubt many subsequently told this tale over a pint of ale – and cast themselves as the hero.

ARMOUR PEIRCING

You can see in the panorama a representation of the shell passing through 24 inch wrought iron. In 1863 Captain William Palliser invented a method of casting shot with the point in an iron mould. This cooled the point more rapidly and produced a brittle, but extremely hard, tip – which enabled a shell from the 100 ton gun to penetrate 24.9 inches of wrought iron. A formidable prospect in an age when the best protected vessels only had armour plating 18 inches thick.

AIMED BY TELEPHONE

Information necessary to aim the gun was conveyed to a telephonist by range-finders situated higher up the Rock. Since the telephone had only recently been invented in 1876, this post of telephonist must have been one of the first in the British army. However, this use of ‘new’ technology contrasts vividly with the fact that commands within the battery itself were still conveyed by speaking tubes and trumpet calls.

The steps shown in the panorama lead upwards to the loading chamber. The tunnel adjacent to the steps lead to the gun via additional steps.

EXTRACT FROM GIBRALTAR CHRONICAL

Gibraltars oldest serving daily newspaper reported the instalation of the gun at the time.

The first of the 100-ton guns was successfully lowered to its carriage in the Napier of Magdala battery yesterday morning in the presence of His Excellency Lieut.-General Sir John Adye, G.C.B., attended by Lieutenant Adye, A.D.C., Sir Henry Burford-Hancock, Captain the Hon. E. Fremantle, R.N., the Colonel on the Staff C.R.A., the Colonel on the Staff C.R.E., Colonel Brackenbury, C.R.A., South District, Majors Caulter R.E., Georges, R.A., Buckle, R.A., and others. The different operation of getting the gun into position from the time of its removal from the hold of the Stanley has been carried out without misadventure, under the immediate supervision of Captain Daniell, R.A., assisted by Lieut. Sankey, R.A., on the part of the Artillery, and of Lieut. Shaw on the part of the Engineers. The following extract from a Dover paper in respect to the firing from the 81-ton gun at that place may prove of interest to our readers, inasmuch as it cannot fail to quiet the minds of those of may have had misgivings as to the effect of the practice from the 100-ton gun at this place. Some time must necessarily lapse where practice can take place, of which due notice will be given in these columns………………………

Loading chamber (B)

Like a gigantic cannon, the gun was muzzle loaded using hydraulically powered ramrods 45 feet long. Their bristled heads were located in two armour plated loading chambers, approximately 8ft in diameter, situated on either side of the gun. In order to load, the barrel was turned first to one chamber to receive its silk cased charges of black prism gunpowder – and then traversed 180 degrees to the opposite chamber to receive a shell.

The official handbook details the duties of the 23 men of all ranks that were required to operate the 100 Ton Gun. However, by using only one loading chamber, a detachment of 15 men could manage, although their rate of fire would have been much slower. In addition, there would also have been a trumpeter, several rangefinders and a telephonist.

It took a total of 450lbs of black prism gunpowder packed into 4 silk cartridges to propel the 2000lb shell out of the muzzle with a speed of about 1540ft per second. which gave the projectile a smashing effect of 33,230ft/ton, allowing it to penetrate 24.9 inches of wrought iron. The normal rate of fire of the Gun was one round every four minutes and it required 35 men of all ranks to serve the gun. The cartridges were made of silk because this was almost entirely consumed by the explosion, leaving very little residue in the barrel.

Silk cartridge

Three types of shell were designed for use with the gun, Common, Shrapnel and Case Shot. The diagrams below are roughly taken from the more detailed drawing at the exhibit.

HAZARDS WITH FIRING

by design the gun could fire a round every four minutes, – but Lieutenant Colonel Ogilvie’s detachment reduced this time to two and a half minutes, which possibly contributed to the splitting of the original barrel. This gun was obviously considered the more important of the two on Gibraltar since the barrel was replaced with that from the other gun, situated where the Fire Station now stands. The day before firings of the gun, the Gibraltar Chronicle warned people to leave their windows open and take fragile objects down from shelves.

100 Ton Gun (C)

The 17.72 inch Rifled Muzzle loader, or 100 Ton Gun, has a barrel length of 32.65ft, of which 30.25ft are rifled and was capable of firing up to 8 miles.

THREE HOURS NOTICE

Such an enormous weapon was not easily manoeurvered, or even loaded, by hand and so a sophisticated hydraulic system was devised. A steam engine pumped water into the bottom of a well, forcing an 85ton piston up the shaft. It was this weight compressing the water beneath it which provided hydraulic pressure to move the gun. Although the official hand book states that sufficient pressure could be achieved in 35 to 50 minutes – a minimum of 3 hours is often quoted.

What seems today to be a ridiculously long response time was probably adequate for an era in which most ships still had sails. It took a Man O’war at least 3 hours to enter the bay of Gibraltar after being sited off the point of Tarifa in Spain.

RECOIL

After the discharge the barrel mounted on the sliding carriage had a backward metal to metal recoil of 5 feet, 9 inches. The sliding carriage and barrel mounted on the 18 solid steel rollers, travelled and ran back on the guide bars mounted on the girder construction of the platform. Shock absorbing pistons conected to a water tank at the rear of the gun carriage caused water to be expelled as the force of the recoil came to bear. The water ran down the slope behind the gun.

EXTRACTS FROM GIBRALTAR CHRONICAL

During test firings residents of Gibraltar were warned to leave windows open and secure breakable household items.

We have been asked to state that practice will be carried on from 100-ton gun from Napier of Magdala Battery, at half-past 9 o’clock on Saturday morning, the 10th inst.

When the first test firing took place the chronical covered the event fith the following copy.

The first rounds were fired this morning from the 100-ton gun at Napier of Magdala Battery, commencing at 9.30 o’clock, in the presence of His Excellency Major-General M. Walker, V.C., C.B., and a number of officers, ladies and gentlemen. The experiments were under the immediate direction of Major White, R.A., and Major English, R.E. assisted by Lieutenant Wolley-Dod, R.A. and Lieutenant Shaw, Royal Engineers. The gun was worked by men of the Royal Artillery, and the intricate machinery below the emplacement by the Royal Engineers. Colonel Ravenhill, C.B., C.R.E., and Colonel Brackenbury, C.B., C.R.A., were present. The first round was fired with a blank charge, the second with a half charge and projectile, the third with a three-quarter charge and the fourth with a full charge and projectile. The noise was comparatively insignificant, and we have as yet heard of no damage being done. The huge projectile weighing close on a ton could be watched through its entire course. The experiment seemed to be satisfactory, but we had no time to get any details beyond that the weight of the full charge is 450lbs of prismatic powder and that the round which was fired with a half charge was at a five degree elevation and the first graze of the shot was roughly at 2,000 yards.

Upper level and Muzzel (D)

This location has long been regarded as strategically important because of its ability to protect the entrances to both the main commercial harbour and what was the Royal Naval Dockyard in Rosia Bay. It was in this bay that H.M.S. Victory anchored for repairs after the battle of Trafalgar in 1805, before returning the body of Admiral Lord Nelson to England for burial.

FIELD AND RANGE OF FIRE

The 100 ton gun located here had a 150 degree field of fire and was said to be capable of engaging a target up to eight miles away. This would have covered the Bay of Gibraltar – as well as the Spanish mainland towns of San Roque, Los Barrios and Algeciras. However, it is doubtful that this range was ever actually achieved. More conservative estimates put the gun’s maximum range at around five miles and the official record of armament P.F.G.951 lists the accurate range limit as only 6500 yards (3.7 miles).

INCREASED ACCURACY

To impart rotation to the projectiles in flight and thereby increase their accuracy, the inside of the barrel was rifled with 28 twisting grooves. Large copper discs, called gas checks, originally used to stop exploding gases ‘leaking’ past the projectile, also served to impart the spin with projections to engage in rifling.

During WW2 provision was made for four 3.7inch anti-aircraft guns approximately 50yds apart along this cliff-top extending northward from here. If you rotate the panorama you will see the one remaining gun in its original position.

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