Font size






100 ton gun to include the two loading rammer chambers and 3.7” AA Gun

Ref: HLFP3/001

The 100-ton gun (also known as the Armstrong 100-ton gun) was a 17.72 inches (450 mm) rifled muzzle-loading (RML) gun made by Elswick Ordnance Company, the armaments division of the British manufacturing company Armstrong Whitworth, owned by William Armstrong. The 15 guns Armstrong made, were used to arm two Italian battleships (the Duilio and her sister-ship Dandolo) and, to counter these, British fortifications at Malta and Gibraltar.

Following Colonel Jervois’ recommendation in 1868 for a heavy RML battery for this area two heavy 17.72-inch 100-ton RML guns on a barbette Mark I mounting were commissioned – one for the Napier of Magdala Battery covering the approaches of Gibraltar at Rosia and one at Victoria Battery on the Red Sands which dominated most of the bay. The total cost of works was of £35,707.

Napier of Magdala Battery.

Diagram showing construction of British RML 17.72 inch gun.

RML 17.72 inch 100-ton gun emplacement diagrams.

The guns were delivered to Gibraltar aboard the WD vessel SS Stanley. The first gun arrived on the 3rd December 1882 and landed on the quay next to New Mole Battery on the 10th December. It was hoisted to the top of that battery using a specially built traveller apparatus between the 4th and 8th June and from there transported by means of a special sleigh to Napier Battery, a distance of 400 yards, which took working 21 days – starting on the 14th June and completed on the 11th July. The gun was finally mounted on its carriage on the 23rd July 1883.

These new artillery pieces were enormous weapons for their time. They were muzzle-loading guns, with a rifled tube and rigid mount. Each gun required a crew of 35 men, including 18 men to handle the ammunition. The gun crews, however, could only fire a projectile once every six minutes.

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. Nevertheless, commands within the battery itself were still conveyed by speaking tubes and trumpet calls.

William armstrong factory production of a 100 Ton Gun.

Shipping the 100-ton gun for the Italian Navy.

Two 100-ton guns aboard the Duilio, 1880.

The first firings took place in 1884, but the weapons were not fully operational until 1889 due to hydraulic system problems. The barrel on the gun at Napier cracked during firing trials; this was because the crew had managed to stress the gun by firing one shot every 2.5 minutes. The barrel was dismounted and replaced by the one at Victoria Battery as Napier Battery was considered the better of the two sites. The wrecked gun was not easily repairable and was eventually removed from the Approved Armament by the authority of the Statement of Changes No. XXXIII dated January 1906 but it was never scrapped and remained in quite good condition. The barrel remained in the ramp of the battery until this was covered when the new office building was built over it.


100 Ton Gun/Landing of one of the 100 ton guns at Gibraltar.

100-ton gun being installed at Napier of Magdala Battery.

The guns at Napier of Magdala Battery in Gibraltar and at Fort Rinella in Malta have been restored and the respective batteries converted into a historical interpretation centre.

The centre at Gibraltar includes access to the perfectly preserved loading rammer chambers beneath the 100-ton gun. A recent survey (2016) all of the surviving original hydraulic machinery at Napier of Magdala Battery by volunteers of the FWA (Fondazzjoni Wirt Artna) in Malta ascertained the following: The original lift consisted of an iron frame structure which supported a wooden base at the centre of which was fitted a turntable and notch shaped ‘stool’. The latter served for locking the ammunition trolley into place after it was loaded on the turntable and swerved into position lined up for loading. The 100-ton gun ammunition trolleys consisted of a heavy wooden block shaped as a horizontal open ended trough fitted with four-gun metal wheels which enabled it to ride on the trolley rails set into the floor of the ammunition chambers. This trolley was capable of taking both a shell and a cartridge at each stage of loading. The loading would only take place after that the ammunition trolley had risen to the gun floor level and lined up with a loading port positioned in the heavy armoured cupolas which protected the lift shafts. The gun would be traversed and lined with the port. In the process, the gun barrel with dislodge with own weight a heavy cast iron port stopper or cover to expose the port hole. The stopper served to protect the interior of the cupolas and lift shafts from the entry of sparks or any flame when the gun fired or during an engagement. With the gun and trolley perfectly line din position a 35-foot rammer would be activated to push the shell and cartridge in reverse into the barrel of the gun making it ready to be trained on target and fired.

The "Rockbuster" was last fired in 2002 (with a very small signalling charge) to mark the 2002 Calpe Conference between Gibraltar and Malta.

Link to Napier of Magdala Battery

Three Hours Notice to fire.

100 Ton Gun Projectile.

apier of Magdala Battery test firing 100 ton gun 1880's.

100-ton gun at Napier of Magdala Battery 1980's.

100 Ton Gun rear view.

100-ton-gun-working-principle-3d-animation Rinella Battery, Malta.

Firing of the 100-ton gun at Napier of Magdala Battery 2002.

3.7-inch AA Gun

Napier Battery had first been selected as a possible HAA site by the 1925 Committee tasked with identifying the potential problems of the air defence of Gibraltar. Thus during the outbreak of WWII two 3-inch 20 cwt AA guns were transferred to this location from Oil Tanks Battery on the 20th April 1940, but these guns were removed only a few months later to make way for a new battery which was to arrive in Gibraltar with 82 HAA Regt.

On the 7th July 1940, four 3.7-inch AA guns were emplaced around Napier Battery, with one AA gun placed right in front of the 100-ton gun. By the 11th July the battery was ready for action and manned by members of 256 HAA battery of 82 HAA Regt. In June 1942 the battery was manned by members of the Gibraltar Defence Force until the battery was taken over by 596 HAA battery in November 1943 but manning only two of the four guns. In July 1944, they were relieved by members of 441 HAA Battery but the battery was put into care and maintenance by the 5th September 1944 remaining after the war as a site to be manned only in an emergency. The guns were finally removed in March 1956.

In the 1980’s, following renovations at Europa Point one of two AA machine guns mounted at Harding’s Battery was removed and placed in its current position at Napier of Magdala Battery. The other AA gun was placed further South at Parson’s Lodge. 

Lt AA Postion, Napier of Magdala Battery.

3.7-inch AA Gun

100 ton gun to include the two loading rammer chambers and 3.7” AA Gun Image