H.M. surveying vessel "Investigator" was lying in dock at Portsmouth, and was under orders to proceed to sea at the first possible opportunity, her errand being to endeavour to locate and capture the submarine that, it was generally agreed, was still in the vicinity of Spithead.
To cope with the situation a special Bill had been hurriedly introduced into Parliament making it an offence against the Naval Secrets Act for any person to manoeuvre a private submarine within five miles of specified naval ports. The Bill received the Royal assent and became law within thirty-six hours after the escape of the suspect arrest on Southsea beach, an individual who was generally accepted as being the man of mystery, Captain Restronguet.
The fellow's diving gear, or at any rate the major portion of it, remained in the hands of the authorities. After being subjected to a lengthy research at the hands of the Diving School at Whale Island the following report was issued confidentially: "The helmet is of a metal hitherto unknown, possessing all the advantages of aluminium, without the known disadvantages. It is a departure from the usual form, having a ridge-shaped projection in front, possibly to lessen the resistance to the water when moving on the bottom of the sea. The helmet is also valveless, the air, chemically prepared, is by some means kept at a fairly high pressure, sufficient to distend the suit in order to do away with any discomfort to the wearer by reason of the weight of water. The suit is made, not of rubber as was at first supposed, but of an unknown quality of flexible metal. When distended it also presents an edge in front, in order to minimize lateral resistance. How the air is purified is still a secret, the apparatus for so doing having been detached and thrown into the sea by the unknown. A diligent search had failed to produce this important item. Undoubtedly the suit, when complete, is far in advance of any now used in the Service."
A careful watch was maintained along the shore, the coastguards stationed in the district being temporarily augmented by men drafted from more remote places. Yet no trace of the mysterious submarine on the surface was to be seen. How, when and where the craft replenished her fuel necessary for locomotion purposes and her provisions and fresh water completely baffled the naval experts; for a fortnight had elapsed since she announced her appearance at Spithead, and save for the temporary visit to Cherbourg all evidence pointed to the fact that she was still within the limits of the Port of Portsmouth.
Arnold Hythe duly joined the "Investigator" as officer in charge of the diving parties. Twelve first-class seamen-divers were drafted into the ship, while special gear for "creeping" was placed on board. Submarine apparatus for recording by sound the presence of submerged craft under way was also installed, so that it was impossible for any vessel making the faintest noise to approach within two miles of the "Investigator." Even the wavelets lapping the bows of a passing fishing-smack would be reproduced with unerring fidelity. Just before high water the "Investigator" was undocked; steam was soon raised, for the surveying vessel, being of an old type, was driven by reciprocating engines and oil-fed boilers. Almost at the moment of casting off the hawsers and springs came news that caused the greatest disappointment amongst officers and crew.
Captain Restronguet had, according to the latest report, turned up in a totally different spot. This time he devoted his attention to the German port of Wilhelmshaven. Here his visit was not of a comparatively harmless nature, for the locks of the Kaiser Wilhelm Canal were totally demolished by means of a powerful explosive. The battleship, "Karl Adelbert," that was about to pass out of the canal, was badly damaged. In the confusion six destroyers and submarines were ordered from Cuxhaven. They were quickly on the spot, but no trace of the mysterious submarine was to be seen, except a small barrel painted white and green, with the name "Captain Restronguet" in bold letters.
The "Investigator" was immediately ordered to make fast one of the buoys in Portsmouth harbour. Her special mission was, for the time being at least, over; a far more serious situation had arisen.
The German Government, supported almost entirely by the Press of that country, actually suggested that, since Captain Restronguet had committed an act of piracy against the German Fleet while he had refrained from so doing on his visit to Portsmouth and Cherbourg, Great Britain and France were secretly aware of the identity of this modern buccaneer, and that they had encouraged him to make an unlawful act of hostility towards a friendly Power.
Three army corps were hastily ordered to Hanover and Schleswig-Holstein, the German High Sea Fleet was ordered to assemble at a rendezvous off Heligoland, and every available battleship, cruiser, destroyer and submarine in the Baltic was sent through the Great Belt and around the Skaw to augment the naval armament already in the North Sea.
The British Government met the situation with promptitude, firmness, and calmness. The First and Second Home Fleets settled at the Nore; the Third Home Fleet, which happened to be cruising off the Orkneys, was ordered to the Firth of Forth. Troops were quickly entrained at Aldershot and Salisbury Plain for the defence of the East Coast, while the Territorial Army and the National Reserve were called up for garrison duty. At the same time a statement was made to the German Ambassador in London in which His Majesty's Government totally repudiated the suggestions that Captain Restronguet held any authority, either direct or indirect, from the Crown.