“A destroyer driving directly at us at full tilt with all her guns in action!” roared McClure.

At the same moment he touched off another torpedo; but, in his eagerness for another “bull’s eye” the American commander had fired too soon, and the torpedo shot past the destroyer, missing the mark by ten yards.

In retaliation, the forward guns of the German craft belched forth a salvo of leaden hail that followed the path of the searchlight’s rays directly upon the eyes of the Monitor.  With unerring aim the German gunners had found their mark.  A sharp crash; a roar as the water above the Monitor’s conning tower was converted into a boiling maelstrom, and the impact of steel against steel betokened the fact that a shot had struck home in the superstructure of the attacking sub.

“Our periscope’s cutoff clean as a whistle,” exclaimed McClure as he backed away from the tube through which he had been observing the approach of the enemy craft.

“Quick, lower away!” he commanded.

Shipping ballast in all her tanks, the Monitor began dropping into the depths.

“Look, look!” yelled Jack as he pointed to the steel dome roof of the conning tower.

In consternation McClure and Ted followed the extended finger to a spot in the steel casement where a jagged hole had been torn by a fragment of the German shell fire and where now a thin stream of water was percolating through the crevice.

“We’ve got to submerge, boys; that destroyer is almost on top of us now!” cried McClure in frenzied tones.  “Get down into the control chamber—–­hurry!” he commanded.

Ted dived down the hatch as fast as he could scramble, followed closely by Jack, who observed by now a steady stream of water pouring into the turret of the Monitor and splashing on clear through to the flooring of the chamber deep down into the hold.

As Jack lowered himself away into the inner chamber amidships the Monitor was clutched suddenly by a terrific explosion that rocked the already crippled submarine with the force of a hurricane and swamped it as though by a tidal wave.  She quivered under the whip of the mighty lash of steel from above.

The German destroyer, driving full speed at the spot where they had sighted the periscopes of the American tormentor, had crossed directly over the Monitor and dropped a depth bomb that had exploded nearly upon the turret of the doughty fighter!

A great gap was torn in the turret through which the sea swept in a torrent.  Fighting madly for the exit hatch into the chamber below, McClure was dashed off his feet by the lurch of the smitten submarine and sprawled against the steel side of the conning tower.  With the spray dashing in his face Jack had a fleeting glimpse of his commander, and by a superhuman effort drew himself back into the turret against the mass of water.  Hurling himself forward, he groped about for his captain and found him finally on the floor of the turret.  Exerting all his strength, he succeeded in hurling “Little Mack” down into the control chamber.