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."

This was done and the U-6 did not come to the surface again until her
commander felt sure that he had no longer need to fear the single
remaining German battleship. Then, upon the surface again, Lord
Hastings, Frank and Jack ascended the bridge.

Through their glasses, far back, they could still see the German
battleships, which, though wounded unto death, were still afloat,
apparently battling desperately to resist the sea that was trying to
draw them und