A huge, black shape loomed up into the moonlight. As she came nearer Lennard could see that the vessel carried a big mast forward with a fighting-top, two funnels a little aft of it, and two other funnels a few feet forward of the after mast.

Erskine put his glasses up to his eyes and said:

"That's the Dupleix, one of the improved Desaix class. Steams twenty-four knots. I suppose she's been shepherding those destroyers that we've just finished with. I hope she hasn't seen what happened. If she thinks that they've got in all right, we've got her. She has a heavy fore and aft and broadside gunfire, two 6.4 guns ahead and astern and amidships, in pairs, and as I suppose they'll be using melinite shells, we shall get fits unless we take them unawares."

"And what does that mean?" asked Lennard.

"Show you in a minute," answered Erskine, touching three or four of the buttons on the right-hand side as he spoke.

Another shudder ran through the frame of the Ithuriel and Lennard felt the deck sink under his feet. If he hadn't had as good a head on him as he had, he would have said something, for the Ithuriel sank until her decks were almost awash. She jumped forward again now almost invisible, and circled round to the south eastward. A big cloud drifted across the moon and Erskine said:

"Thank God for that! We shall get her now."

Another quarter turn of the wheel brought the Ithuriel's head at right angles to the French cruiser's broadside. He took the transmitter of the telephone down from the hooks and said:

"Are you there, Castellan?"

"Yes. What's that big thing ahead there?"

"It's the Dupleix. Ready with your forward guns. I'm going to fire first, then ram. Stand by, centre first, then starboard and port, and keep your eye on them. These are Mr Lennard's shells and we want to see what they'll do. Are you ready?"

"Yes. When you like."

"Half speed, then, and tell Mackenzie to stand by and order full speed when I give the word. We shall want it in a jump."

"Very good, sir. Is that all?"

"Yes, that's all."

Erskine put the receiver back on the hooks.

"That's it. Now we'll try your shells. If they're what I think they are, we'll smash that fellow's top works into scrap-iron, and then we'll go for him."

"I think I see," said Lennard, "that's why you've half submerged her."

"Yes. The Ithuriel is designed to deal with both light and heavy craft. With the light ones, as you have seen, she just walked over them. Now, we've got something bigger to tackle, and if everything goes right that ship will be at the bottom of the sea in five minutes."

"Horrible," replied Lennard, "but I suppose it's necessary."

"Absolutely," said Erskine, taking the receiver down from the hooks. "If we didn't do it with them, they'd do it with us. That's war."

Lennard made no reply. He was looking hard at the now rapidly approaching shape of the big French cruiser, and when men are thinking hard, they don't usually say much.

The Ithuriel completed her quarter-circle and dead head on to the Dupleix, Erskine said, "Centre gun ready, forward—fire. Port and starboard concentrate—fire."

There was no report—only a low, hissing sound—and then Lennard saw three flashes of bluish-green blaze out over the French cruiser.

"Hit her! I think those shells of yours got home," said Erskine between his clenched teeth. And then he added through the telephone, "Well aimed, Castellan! They all got there. Load up again—three more shots and I'm going to ram—quick now, and full speed ahead when you've fired."

"All ready!" came back over the telephone, "I've told Mackenzie that you'll want it."

"Good man," replied Erskine. "When I touch the button, you do the rest. Now—are you ready?"

"Yes."

"Let her have it—then full speed. Ah," Erskine continued, turning to Lennard, "he's shooting back."

The cruiser burst into a thunderstorm of smoke and flame and shell, but there was nothing to shoot at. Only three feet of freeboard would have been visible even in broad daylight. The signal mast had been telescoped. There was nothing but the deck, the guns and the conning-tower to be seen. The shells screamed through the air a good ten feet over her and incidentally wrecked the Marine Hotel on Selsey Bill.

Erskine pressed the top button on the right-hand side three times. The smokeless, nameless guns spoke again, and again the three flashes of blue-green flame broke out on the Frenchman's decks.

"Good enough," said Erskine, taking the transmitter down from the hooks again. "Now, Mr Lennard, just come for'ard and watch."

Lennard crept up beside him and took the glasses.

"Down guns—full speed ahead—going to ram," said Erskine, quietly, into the telephone.

To his utter astonishment, Lennard saw the three big guns sink down under the deck and the steel hoods move forward and cover the emplacements. The floor of the conning-tower jumped under his feet again and the huge shape of the French cruiser seemed to rush towards him. There was a roar of artillery, a thunder of 6.4 guns, a crash of bursting shells, a shudder and a shock, and the fifty-ton ram of the Ithuriel hit her forward of the conning-tower and went through the two-inch armour belt as a knife would go through a piece of paper. The big cruiser stopped as an animal on land does, struck by a bullet in its vitals, or a whale when the lance is driven home. Half her officers and men were lying about the decks asphyxiated by Lennard's shells. The after barbette swung round, and at the same moment, or perhaps half a minute before, Erskine touched two other buttons in rapid succession. The Dupleix lurched down on the starboard side, the two big guns went off and hit the water. Erskine touched another button, and the Ithuriel ran back from her victim. A minute later the French cruiser heeled over and sank.

"Good God, how did you do that?" said Lennard, looking round at him with eyes rather more wide open than usual.

"That's the effect of the suction screw," replied Erskine. "I got the idea from the Russian ice-breaker, the Yermack. The old idea was just main strength and stupidity, charge the ice and break through if you could. The better idea was to suck the water away from under the ice and go over it—that's what we've done. I rammed that chap, pulled the water away from under him, and, of course, he's gone down."

He gave the wheel a quarter-turn to starboard, took down the transmitter and said: "Full speed again—in two minutes, three quarters and then half."

"But surely," exclaimed Lennard, "you can do something to help those poor fellows. Are you going to leave them all to drown?"

"I have no orders, except to sink and destroy," replied Erskine between his teeth. "You must remember that this is a war of one country against a continent, and of one fleet against four. Ah, there's another! A third-class cruiser—I think I know her, she's the old Leger—they must have thought they had an easy job of it if they sent her here. Low free board, not worth shooting at. We'll go over her. No armour—what idiots they are to put a thing like that into the fighting line!"

He took the transmitter down and said:

"Stand by there, Castellan! Get your pumps to work, and I shall want full speed ahead—I'm going to run that old croak down—hurry up."

He put the transmitter back on the hooks and presently Lennard saw the bows of the Ithuriel rise quickly out of the water. The doomed vessel in front of them was a long, low-lying French torpedo-catcher, with one big funnel between two signal-masts, hopelessly out of date, and evidently intended only to go in and take her share of the spoils. Erskine switched off the searchlight, called for full speed ahead and then with clenched teeth and set eyes, he sent the Ithuriel flying at her victim.

Within five minutes it was all over. The fifty-ton ram rose over the Leger's side, crushed it down into the water, ground its way through her, cut her in half and went on.

"That ship ought to have been on the scrap-heap ten years ago," said Erskine as he signalled for half-speed and swung the Ithuriel round to the westward.

"She's got a scrap-heap all to herself now, I suppose," said Lennard, with a bit of a check in his voice. "I've no doubt, as you say, this sort of thing may be necessary, but my personal opinion of it is that it's damnable."

"Exactly my opinion too," said Erskine, "but it has to be done."

The next instant, Lennard heard a sound such as he had never heard before. It was a smothered rumble which seemed to come out of the depths, then there came a shock which flung him off his feet, and shot him against the opposite wall of the conning-tower. The Ithuriel heeled over to port, a huge volume of water rose on her starboard side and burst into a torrent over her decks, then she righted.

Erskine, holding on hard to the iron table to which the signalling board was bolted, saved himself from a fall.

"I hope you're not hurt, Mr Lennard," said he, looking round, "that was a submarine. Let a torpedo go at us, I suppose, and didn't know they were hitting twelve-inch armour."

"It's all right," said Lennard, picking himself up. "Only a bruise or two; nothing broken. It seems to me that this new naval warfare of yours is going to get a bit exciting."

"Yes," said Erskine, "I think it is. Halloa, Great CÆsar! That must be that infernal invention of Castellan's brother's; the thing he sold to the Germans—the sweep!"

As he spoke a grey shape leapt up out of the water and began to circle over the Ithuriel. He snatched the transmitter from the hooks, and said, in quick, clear tones:

"Castellan—sink—quick, quick as you can."

The pumps of the Ithuriel worked furiously the next moment. Lennard held his breath as he saw the waves rise up over the decks.

"Full speed ahead again, and dive," said Erskine into the transmitter. "Hold tight, Lennard."

The floor of the conning-tower took an angle of about sixty degrees, and Lennard gripped the holdfasts, of which there were two on each wall of the tower. He heard a rush of overwhelming waters—then came darkness. The Ithuriel rushed forward at her highest speed. Then something hit the sea, and a quick succession of shocks sent a shudder through the vessel.

"I thought so," said Erskine. "That's John Castellan's combined airship and submarine right enough, and that was an aËrial torpedo. If it had hit us when we were above water, we should have been where those French chaps are now. You're quite right, this sort of naval warfare is getting rather exciting."