t last came the moment when the commander of the submarine flotilla
decided to climb to the surface and make an observation.

With every man standing to his post of duty and every nerve strained
for the next move, the signal to pump out ballast was given and the
_Monitor_ turned her diving rudders to ascend. Soon her periscopes
thrust their eyes out of the depths.

"Look! there, off our port bow!" exclaimed Jack to his chief.

McClure saw it, too, at the same moment---a giant German battle
cruiser lying broadside to the harbor entrance and every gun belching
forth fire at the allied fleet outside!

Responding to the control of her commander, the _Monitor_ swung off
sharply to port and drove straight for the cruiser.

McClure's right hand groped for the torpedo button as he sighted
on the German battle cruiser. He released a torpedo!

CHAPTER XXV

CHLORINE GAS

Confident of security behind the mass of mines and submarine traps
spread ingeniously across the harbor entrance, devoting their attention
almost solely to the artillery duel with the dreadnoughts outside, the
German cruiser knew naught of the stealthy torpedo from the daring
_Monitor_ until it shot suddenly forward below the surface of the
water, revealed in the glare of her own searchlight. But it was
too late then to avoid the deadly missile and it struck home abaft
the engines and directly at the after magazine chambers. With a great
roar and the upheaval of a mighty column of water the torpedo exploded
against the side of the warship. One carefully aimed shot from the
leading American submarine had laid low a ten-thousand-ton cruiser!

"Quick, down we go!" shouted McClure to his navigating officer. The
_Monitor_ shot down now out of sight, and the helm was thrown hard to
starboard. That one shot was sufficient to apprise the Germans of
the presence of submarines and McClure realized full well he would be
a marked man next time he showed his periscopes above water.

It was in mid-channel that the _Monitor_ ventured to the surface
again. The periscopes showed another vessel, a second line battleship
of the pre-dreadnought type, off the starboard beam. Undaunted by
the hail of lead slugs that splashed the sea all around, the _Monitor_
swerved and ran straight for the battleship's bows.

"This one ought to settle scores for that poor old mine sweeper!"
yelled the Yankee skipper as he sighted through the periscope glass
on the wide ta