Heavily depressed, the gun barked, sending the shell obliquely towards the surface of the water. Fifty feet in the air flew a column of spray, while the torpedo, deflected by the impact of the missile, tore harmlessly past R19's hull.

The U-boat, having shot her bolt, was preparing to dive once more, although her conning-tower had not appeared above the surface.

With a dull crash and a scarcely-perceptible shudder R19's snub-nosed stem grated against the rounded side of her foe. So great was her momentum that her bows were lifted clear of the waves.

"Got her, by smoke!" ejaculated the Hon. Derek, who, having emerged from the conning-tower, was standing by the side of Fordyce on the navigation-platform.

Both officers turned and faced aft. They were just in time to see the bows of the U-boat fling themselves clear of the agitated waves—sufficiently to enable them to note the number, U129—then, with a sobbing, gurgling sound, the doomed craft slithered beneath the surface, to the accompaniment of a volume of iridescent oil and a crowd of huge air-bubbles.

"Have a look down below, Mr. Fordyce," continued the Lieutenant-Commander. "Let's hope we haven't started a plate or two. It would be rough luck at this stage to have to put back for repairs."

The Sub hastened to carry out his instructions. Eager faces mutely questioned him as he entered the electrically-lighted compartment where the "hands" not told off for duty on deck were still in ignorance of what had occurred, although the unexpected shock had been sufficient to capsize several of the crew.

"It's all right, men!" exclaimed the Sub cheerily. "We've strafed another U-boat. The Zepp., I'm sorry to say, has sheered off."

In answer to his enquiries, Fordyce learnt that immediately after the impact steps had been taken to ascertain if any damage had been done to the hull. Not a leak was to be found. The for'ard diving-planes or horizontal rudders were intact and in perfect working order; while, on testing the twin bow torpedo-tubes, both were found to be undamaged. Evidently R19 had not struck her opponent an end-on blow, otherwise the covers of the tubes would have been buckled or burst from their hinges. At the moment of impact U129 had submerged sufficiently to allow her opponent to strike a glancing blow with her forefoot—enough to crack the deck-plates of the ill-starred unterseeboot.

Eager to convey this gratifying report to his skipper, Fordyce went on deck. As he emerged through the circular man-hole a burst of cheering greeted his ears. He was just in time to see a long trailing cloud of fire-tipped smoke plunging towards the water at a distance of less than a couple of miles to leeward.