CHAPTER VIII

Balked by a Sea-plane

"How so?" demanded Kapitan Schwalbe. "If we keep quiet, the cruiser--for cruiser she must be, judging by the fellow's description--will weigh and proceed."

"When she does weigh we are undone," said Rix despondently. "We are swinging round our anchor. For all we know, our cable has taken a turn round hers. As soon as they heave up their anchor, our anchor and cable will be brought up with it, and then the game is up. Either the strain will overcome our dead weight and we will be hauled to the surface, or else they'll lower one of their brutal explosive charges."

"The situation is serious," admitted Schwalbe in a low tone, for his Leutnant's words had produced a demoralizing effect upon the men. "How much cable have we inboard?"

Rix repeated the question. A petty officer doubled forward to consult the cable indicator. U75's anchor, when under way, was housed in a trough on the under side of the submarine's forefoot. The cable was automatically ranged in a compartment between the inner and outer skins, the space being always filled with water. The inboard end of the cable was not shackled; but to prevent its being able to take charge and run out, an indicator was placed on the bulkhead nearest to the cable tier. The amount of chain let go was regulated by a compressor, which was actuated from within the hull by means of levers and cranks, watertight glands being provided to prevent any leakage into the interior of the submarine.

"Seventy-five fathoms," reported the petty officer. "When we commenced to swing we paid out the length we had taken on board when we hove short."

"We must sacrifice the lot, Herr Rix," decided Kapitan Schwalbe. "There is no time to lose. Storm or no storm, we must slip and run for it."

It was U75's only chance, but it left her with only a small stockless kedge-anchor and chain, insufficient to withstand a heavy strain.

The compressor was released. With a loud rumble, for every sound was magnified within the confined space, the rest of the cable was allowed to take charge. It did so promptly, the end of the chain giving the hull a defiant smack as it did so. U75, no longer held by her anchor, began to drift with the tide, scraping dismally over the bed of Helwich Channel.

Schwalbe was now back at his post in the conning-tower. He dare not take the submarine to the surface until he had put a safe distance between him and the anchored British warship. Nor did he care to order the ballast tanks to be blown. Rather than allow the "pumping" of the seas to hammer the submerged craft upon the hard sand, he preferred to take the risk of letting her drag.

Fortunately the tide set evenly along the bed of the channel. A cross-current would have set the submarine upon the jagged rocks of the hidden West Helwick Ridge. Nevertheless there was always the danger of being hurled violently against a detached rock, or of fouling a live mine if by chance the British had laid obstructions in the channel.

Both Ross and Vernon knew the danger, but, manfully concealing their misgivings, they watched the faces of those of the crew who were "watch below". Most of the men were Frisians, broad-shouldered, blonde-featured, and generally devoid of fear. Yet the ceaseless strain upon the nerves had already begun to tell. As hardy fishermen, they would not have hesitated to launch their open boats in a storm to go to the rescue of a hapless vessel aground on the grim sand-banks of the Frisian shore. As the conscript crew of the submarine, compelled to keep within the limits of a steel box that almost momentarily threatened to be their tomb, their natural bravery was quenched.

Many of them sat upon their lockers, stolid-faced men who had already tasted of the bitterness of death. Others showed unmistakable signs of excitement, bordering on frenzy. They dreaded their life of modern piracy. The idea of sinking hapless merchantmen was repugnant to them, for they understood the brotherhood of the sea. It would be different if they were called upon to attack an armed British ship of war. They had no option but to obey their junker officers, who in turn were compelled to accept the misguided orders of the arch-pirate, von Tirpitz.

They were disheartened, too, for reports, in spite of the vigilance of the officers to conceal them, had reached them of the losses inflicted upon other unterseebooten. Occasionally they heard of a submarine crew being saved, but generally it was a case of total loss of all on board, by some hitherto unknown means, at the hands of the British Navy.

A hand touched Ross lightly on the shoulder. Turning, he saw Hans Koppe standing in a darkened corner of the compartment.

"Can you tell me this, mein herr?" asked the seaman in a low tone. "Is it true that the English give no quarter to German seamen in submarines?"

"I shouldn't think that they would refuse to do so," replied Trefusis. "Of course, I can quite understand that an opportunity doesn't often occur; but I've heard of several instances in which your U-boats have surrendered, and the crews have been treated exactly the same as other prisoners of war."

"I have heard differently," said Hans, "but I hope it's a mistake. I have a feeling that we won't see Wilhelmshaven again. And I have a wife and six children at Flensburg. Our Kapitan, too, expects that we might be denied quarter, because we have sunk your merchantmen. Believe me, I regret having done so, but we have orders. Do you know why Kapitan Schwalbe took you on board?"

"Because a certain German agent wanted us out of the way, I suppose," replied Ross.

"Perhaps," admitted Hans Koppe. "But in the event of our being captured he thinks that his good treatment of you will be in his favour. We are, I do not mind telling you, in a very tight corner. Our fuel supply is almost run out. We cannot hope to return home by way of the Straits of Dover. Not one of our submarines has tried that passage of late without meeting with disaster--at least, so I heard der Kapitan tell der Leutnant. Ach! It is deplorable, this war."

The rapid ringing of a gong was the signal for the watch below to turn out. A peculiar hissing noise proclaimed the fact that the ballast tanks were being emptied. U75 no longer grated over the bottom; her motors were running almost dead slow.

Although submerged, the submarine was "pumping" violently. Seasoned men were prostrate with sea-sickness. The air, in spite of chemical purifiers, was becoming almost intolerable. Everything movable was being thrown about in utter disorder, while to add to the discomfort of the crew the covering-plates of one of the lubricating-oil tanks had been strained, and at every jerk jets of viscous fluid would squirt through the fracture and trickle sullenly over the floor of the crew-space.

Since the watertight doors were still closed, Ross and Vernon were unable to get back to their bunks. Feeling thoroughly wretched, they were glad to accept Hans Koppe's offer to lie down on a long locker.

At noon, U75 came to the surface. The storm, being short forecasted, had quickly blown itself out, but the waves still ran high.

It was a prearranged plan on the part of the three U-boats operating in the English and Bristol Channels to communicate with each other by wireless at noon and at midnight. U75's wireless had a range of about 180 miles, and although it could be "jammed", the call could not be tapped by vessels other than the one for which it was intended. To make doubly sure, the messages were sent in code.

For nearly ten minutes U75 "made her number" without eliciting any reply. Perhaps it was well that Kapitan Schwalbe did not know what had happened to her consorts. U74 was at that moment lying on her side at the bottom of a Welsh harbour, her crew poisoned by the chlorine fumes from her batteries--the result of a rash curiosity on the part of her Lieutenant-Commander to investigate the approaches to the anchorage. As for U77, she was flying blindly for safety, with a couple of destroyers hard on her track, and a naval sea-plane overhead to direct them in their search.

Foiled in her efforts to get in touch with her consorts, U75 remained awash. The heave of the sea made it most difficult for her to use her periscope with certainty, for she had chosen a bad pitch on her ascent--the furious "overfalls" or "tide-rips" to the west of Lundy Island.

"We'll pay another visit to St. Mena's Island, Herr Rix," decided Kapitan Schwalbe, after the two officers had discussed the sinister matter of their futile attempt to make use of the wireless. "To-night at nine o'clock ought to suit. If we cannot get von Ruhle to see our signals--for my own part, I doubt whether he is in these parts--we'll have to do our best to get ashore. Meanwhile, keep a bright look-out. If we see any likely vessel coming this way, we'll try our luck once more."

"Message just received, mein herr," announced the wireless operator.

"From whom?" enquired Kapitan Schwalbe eagerly. He was devoutly hoping that either U74 or U77 had been able to "call up".

"I cannot say, sir," replied the man as he handed a code message to his superior.

Decoded, the "wireless" was as follows:

"Station 41 to unterseebooten. Two hundred gallons of fuel available here. Will be on the look-out for signals at 1 a.m."

The message was a "general call" for a secret petrol depot to any German submarine operating in the vicinity. Reference to the list of stations showed that "41" was at Port Treherne, a remote cove on the North Cornish coast about fifty miles from St. Mena's Island.

"I suppose it's safe," remarked Rix.

"With due precautions--yes," rejoined Kapitan Schwalbe. "At any rate, petrol we must have. Where's the chart? Ah, there we are! It looks a fairly easy place to approach, don't you think? The only danger from a navigation point is apparently this ledge of rocks--Lost Chance Reef, it's called. What unpleasant names these Englishmen give to their coasts!"

At that moment the Unter-leutnant, who happened to be at the conning-tower periscope, reported that a large vessel was bearing down towards them.

Kapitan Schwalbe hurried to the conning-tower. The object depicted was that of a modern tank-vessel about four hundred feet in length. She was low in the water, showing that she was well laden. In place of masts she had four stumpy poles supporting derricks. Right aft was the single funnel. The navigation bridge was well for'ard, connected with another bridge just in front of the funnel by a long slender gangway.

"An oil-tank homeward bound!" exclaimed Kapitan Schwalbe. "Just what we want to fall in with. All being well, there will be no necessity to visit either Port Treherne or St. Mena's Island. Ach! When we have taken what we require we will set fire to the ship, and the English will have a splendid view of a maritime bonfire."

The crew were ordered to their stations, the ballast tanks "blown", and U75 rose to the surface instead of "running awash", since the Kapitan had resolved to stop the tank by gun-fire.

Even then the waves were running so high that the guns' crews were almost constantly up to their knees in water.

Somewhat to the surprise of the submarine's officers and crew, the tank-steamer made no attempt to escape. The firing of a shot across her bows and the display of the black cross ensign were enough to cause the skipper to reverse her engines.

In less than five minutes, the oil-vessel was rolling in the trough of the sea and drifting slowly to leeward. Yet it was a somewhat remarkable circumstance that no attempt was made to lower the red ensign that was proudly displayed at the stern.

Kapitan Schwalbe, with his intimate knowledge of navigation, knew that the only way possible to board the prize was to run to leeward of her, and let the hull of the large vessel serve as a breakwater. He also knew that the submarine would have to be constantly under way during the boarding operations, otherwise the tank-vessel, offering considerable resistance to the wind, would drift down upon U75, whose leeway was almost unappreciable.

"Send a boat, and lower your accommodation ladder," ordered Kapitan Schwalbe, who, as the submarine ranged up half a cable's length to leeward of the tank-vessel, had left the shelter of the conning-tower and was standing on the platform in its wake.

"Aye, aye," was the prompt response.

"Board her, Herr Rix," said the Leutnant's superior officer. "Bring back her papers with you. Order them to pump heavy oil both to windward and leeward. We will then be able to run close alongside and receive her hoses."

A boat containing two seamen and an apprentice was lowered from the tank's quarter and rowed to the submarine. Into it dropped Leutnant Rix and half a dozen armed men. With them they took two incendiary bombs fitted with time-fuses.

Rix smiled grimly as he gained the oil-steamer's deck. The captain and first mate were at the head of the accommodation ladder to receive him. Most of the crew were already mustering on deck, each with a bundle containing his private effects.

"You prize to German boat," announced the Leutnant. "Make you no trouble and we you will not harm. First we will haf much oil--petroleum, is it not? Order your engineer to get steam to donkey-engine, and your men--the--the---- Hein! Ach, I haf it--the hoses to get ready. When we fill up, then twenty minutes we give you to clear out. You onderstan'?"

"Perfectly," replied the British skipper, a tall, raw-boned Scot, as he eyed the podgy German Leutnant with grim contempt. "But d'ye ken yon?"

He pointed skywards. Less than five hundred feet up, yet sufficiently far from the tank-vessel to enable the latter to screen her from the unterseeboot, was a large naval sea-plane. It was to deaden the noise of her motors that the ship's steam-pipe was continually blowing off steam from the time that U75 made her peremptory demand.

The eyes of the Leutnant and his six men followed the direction indicated by the British skipper's outstretched hand.

At that instant the sea-plane was visible above the towering sides of the British vessel.

U75 was still forging slowly ahead. In a trice Kapitan Schwalbe decided how to act. Ordering the men on deck to their diving stations, he dropped agilely into the conning-tower and gave the word for the helm to be ported.

Thus, while the quick-firers were being housed, the submarine had drawn close under the oil-tank's quarter. Here she was comparatively safe from the sea-plane, as the latter could not drop any bombs without risk of exploding the highly inflammable cargo of the British vessel.

In ten seconds the sea-plane was over and beyond her quarry. She had then to turn and circle overhead, awaiting the chance of shattering her enemy as she dived.

U75 was already disappearing beneath the waves.

She dived at a very oblique angle, steeper than she had ever done before.

Ross and Vernon, unaware of what was taking place, thought for a moment that the submarine was plunging headlong to the bed of the Bristol Channel. They had to cling desperately to the nearest object to hand to prevent themselves from sliding violently against a transverse bulkhead.

Even as they clung they heard two muffled detonations in quick succession, followed by a distinct quiver of the submarine's hull--a movement that bore a marked difference to the vibrations under the pulsations of the motors.

The sea-plane had dropped two bombs, both of which very nearly attained their object.

Kapitan Schwalbe did not bring the submarine to a horizontal position until she had reached a depth of fifteen fathoms. At that depth he was safe, both from explosives dropped from the sea-plane and also from observation. The water being still agitated, made it impossible for the observer on the biplane to follow the movements of a dark shadow fathoms deep. For once, the rough seas had been kind to U75; but the fact remained that she was still badly in want of fuel, while his last attempt had resulted in the loss of an officer and six men, who could not well be spared.

Although the sea-plane had failed to achieve her object by pulverizing the U-boat's hull, the moral and material result was none the less effective.

The explosion of the bombs had started several of U75's plates. Numerous jets of water were spurting through the seams, the inrush requiring all the mechanical appliances at the command of the modern pirate to keep the leaks under control, while the badly-jarred nerves of Kapitan Schwalbe and his crew warned them of the grave risks they ran in attempting to try conclusions with even an apparently harmless craft displaying the Red Ensign of Britain's Mercantile Marine.