Jack gave the command.

“Twenty knots!” ordered Lord Hastings.

The U-6 leaped forward beneath the water like a thing alive.  For fifteen minutes she sped on and then rose until her periscope showed above the surface.

“As I expected,” said Lord Hastings.  “The enemy is making for home, but we have outrun them and are now between them and their goal.”  He gauged the range carefully and then ordered:  “No. 2 torpedo!”

Again all was expectancy aboard the submarine as all eagerly awaited the next command.  It was not long coming.

“Attention!” the signal board read.

And a moment later came the next command: 

“Fire!”

A shell sped across the water straight for the third German battleship.  Through the periscope Lord Hastings saw the German vessel give a great lurch, then leap almost clear from the water, where it seemed to hang suspended for a full minute, before it came down again.  As it did so there was a blinding flash and a detonation that was heard in the submarine.

“Pierced her magazine!” said Lord Hastings quietly.

He stepped aside that Jack might have a look above.

The latter’s eyes sought out the spot just in time to see the giant battleship split in twain and disappear beneath the sea.  Farther back he saw the two others of the enemy listing badly to port, and knew that they had received their death blow.

The fourth and last vessel was still unharmed and was bearing down on them at full speed.  Even as Jack looked there came a puff of smoke from one of her forward turrets and a great splash, less than a hundred yards ahead of the U-6, told that the submarine had been discovered.

“Submerge!” cried Jack.

Lord Hastings repeated the command immediately for he realized that the vessel must be in danger.  Even as the periscope disappeared from sight, there was a second flash from the German and a shell glanced off the bow, sending the U-6 staggering and hurling the officers and crew to the floor.

The men picked themselves up quickly and all stood silent for a moment.

“Test the pumps quick!” was Lord Hastings’ first command after he had regained his feet.

“No damage there, sir,” came the cheering news a moment later.

“Signal the engine room!  Something may have given way,” ordered Lord Hastings.

This was done, but the engineer reported no damage.

Frank and Jack both breathed easier, as did Lord Hastings.

“A pretty narrow squeak,” remarked Lord Hastings calmly.

“Rather, sir,” agreed Jack dryly.  “And now shall we go after the other one, sir?”

“I guess not,” replied his commander.  “After this day’s work we can afford to let one escape.  There is no use taking further chances.  Besides, she’ll be on the lookout for us and might cripple us the moment we showed ourselves.  No; we’ll head west again and won’t come to the surface until we are well out of this.  You may come about, Mr. Templeton, and proceed due west at ten knots.”