Torpedo warfare demonstrations made an interesting performance for the instruction of the naval and military services in the use of torpedoes and submarine mines took place on the night of Thursday, the 16th October, in front of the shore to the west of Portsmouth harbour, below Haslar Hospital, where Fort Monckton and Fort Gilkicker command the roadstead of Spithead.
These forts are supported by Southsea Castle on the eastern side of the entrance to Portsmouth, also by the Spit Fort and several other batteries, along the shores of a bay two miles wide by more than a mile in radius, which no hostile fleet could enter. The western shore, which is immediately opposite Ryde, in the Isle of Wight, is protected by stone wall and causeway against the encroachments of the sea. At the harbour end is Blockhouse Port, which commands the fairway; at the other end Fort Monckton defends the entrance from the west and prevents a landing any part of the wall.
The plan of the mimic warfare on Thursday week may now be explained. It was supposed that a fleet of the enemy’s ironclads had forced the passage of the Needles and run the gauntlet of Hurst Castle and was preparing to make a night attack upon the dockyard and ships. Before the fleet, however, was able to command the dockyard, it was necessary that a passage should be cleared through a channel defended by submarine mines, supplemented by various kinds of obstructions, floating and fixed.
The fort at Gilkicker and all batteries on the shore were supposed to have been silenced by the fire of the enemy’s ships. The only heavy artillery remaining for the defence of the mines was some of the guns of Fort Monckton. But these were supported by a battery of field artillery (the L battery of the fourth brigade, from Hillsea), and two battalions of infantry, represented by a couple of detachments of ninety men each, furnished by the 24th Regiment and the Marines, under the command of Major Keough, of the 12th Foot.
On the water the defenders had four guard boats, manned marines and bluejackets, under the command of Captain Dowding. The moment of the attack the enemy was understood to have cleared a passage through the advanced mines 120 yards wide to a point within range of the defenders’ guns and was about to dispatch boats forward to remove obstructions and to open by countermining, or by other means, a channel for his fleet through the remainder of the defended approach.
Hence the contest which are describing between the Royal Engineers and the navy, which latter force was represented the Bloodhound, Vesuvius, and Lightning, and six launches from the Vernon and Hecla, the whole being under the command of Captain Gordon.
The channel, the possession of which was so obstinately contested, was bordered on one side by the sea wall already mentioned the other side being an imaginary line, indicated by the Speedy and Medina, tenders, which were moored at wide intervals, and exhibited lanterns in their rigging. The defended area measured 1800 yards long and 800 yards broad. The attacking vessels were obliged to pass over it, breaking out from it either at the end or the sides. In contiguity with the farther or imaginary boundary line there was supposed to be a channel 150 yards wide for the use of friendly or neutral craft entering or leaving the port.
The engineers were obliged to preserve the freedom of the channel, at the same time that they secured its defence. This they accomplished, sinking a number of observation mines, which would not explode either mechanical or electrical contact, but only from connection with the shore after cross bearings had shown that the enemy had approached within the range of the submarine mines.
While these conditions rendered them dangerous only to enemy, the depth at which they were sunk enabled vessels to pass over without coming into collision with them. The remaining breadth of the channel was closed, and it was here that the most exciting part of the contest took place.
Close inshore a number of mechanical mines had been dropped as a precaution against the passage of small creeping craft. These torpedoes exploded by mere percussion, automatically, and without any assistance from the shore. Nearer the middle of the locked channel, and little farther removed from the point of entrance, three nests of buoyant torpedoes had been fixed. These were fired electric contact the moment the enemy’s boats completed the circuit by bumping against them. may thus imagined that the defences were of a very formidable character, especially as their whereabouts could only be determined by creeping.”
This was accomplished by means of grapnels, dragged over the ground where the mines were supposed to be. soon as. the hook fastened upon the moorings of a torpedo or its cable, a small charge of gun-cotton, contained in a canister fixed inside the grapnel, would explode, and the torpedo would be rendered impotent by the fracture of its connections. The Royal Engineers had adopted the unusual precaution of placing colossal boom, 600 yards long and ten inches square, across the closed channel, so that none of the electric cables could be approached until this unexpected barrier had been removed. It was at this point that the battle culminated.
A brilliant ray of electric light was kept constantly playing upon the boom from a lantern worked by seventy Grove’s cells and stationed on board boat moored its shore extremity. The attacking small craft were supposed to be well peppered from the shore, the infantry, stationed on the right and left flanks of the fort, and also within the curtain, keeping up an imaginary fusillade, while the guns and field-pieces on the parapet directed an imaginary mitraille of case and shrapnel (GD note: grapeshot) over the whole area. Colonel Shaw, was in chief command of the land defences; Captain John Kamsay, (the officer in command of the submarine miners), was in special charge of the torpedo arrangements.
In reality, it need not be said, the submarine mines and countermines were harmless. The charges in each case were supposed to represent 500 lb of gun-cotton, and to be worth £5O each. As the explosion of torpedoes of this size would be not only extremely dangerous, but much too expensive, imagination was largely brought into play. Each mine and counter-mine was provided with a ‘‘blowing charge” consisting of a couple of pounds of powder, the exploding of which, either by concussion or electrical contact, being visible, was sufficient to show that the engine was operative and had accomplished its work. Every boat, therefore, which detonated a charge was supposed to have been blown to pieces, and every boat which was found to be within a radius 30 feet of the explosion was obliged to retire from the contest in disabled condition.
The electric light was very largely employed. The lights afloat were on the Wilde principle, while two on the bastions of the fort were generated by a Gramme (please see note at bottom) and a Siemens machine. One of the guard boats carried an M Gramme machine : the light at the boom was worked by a battery formed of Grove’s cells. The attacking flotilla, which had assembled at the harbour rendezvous at nine o’clock in the evening, began cautiously feeling their way into the protected waters from the southwest. The furnaces were screened as much as possible to prevent the glare of the fires being observed by the defenders while the vibrations of their engines were so subdued to make it difficult for the ear to detect their approach.
The guard-boats carried white flags at the stem, while the steam-launches were distinguished from each other by boards being lashed across their funnels. Each hit was recorded by prearranged code of signals, and it was not long before the whole of the six launches belonging the enemy were signalled out of action. Before the whole flotilla, however, was placed hors de combat, one daring steam-launch was observed to tow a rowboat alongside the booms, to which the inmates succeeded attaching charge of dynamite. This was at once exploded, as soon as the hostile craft had retired to a safe distance. The injury was not immediately apparent, but it was subsequently demonstrated to have been sufficiently fractured to allow of the Bloodhound passing through the breach. The Bloodhound itself was the first to begin dropping a line of counter-mines in the midst of the defenders’ torpedoes.
This was one of a projected double line which was intended to sweep a channel 700 yards in length; but as she afforded a clear and comparatively bulky target for artillery, she was disabled and compelled to retire before she could explode them. The Lightning was equally unlucky, notwithstanding her enormous speed and low hull; the Vesuvius, however, was perfectly successful, and was enabled not only to drop the second line of counter-mines, but to explode them ; but whether they fell within the fatal radius of feet remained to be determined by subsequent examination.
At any rate, as the diameter of the destructive energy would only be 60 ft., this was not considered sufficient to admit the passage of an ironclad. Practically, therefore, the safety of the dockyard was not endangered by the enemy’s operations. We are Indebted to an officer of the scientific branch for the sketches that furnish our Illustrations of this affair, which was witnessed by multitude of spectators from the sea wall and from the piers at Portsmouth, besides those privileged to stand on the ramparts of Fort Monckton, including the military attaches of several foreign Embassies