Stockdale acted with praiseworthy caution. The presence of a numerous torpedo-boat flotilla in the rear of the battleship division, and the scouting planes overheard, made it a matter of extreme risk for R19 to draw within effective torpedo range. In the comparatively shallow and clear water her submerged hull would be clearly visible from a height. Directly the long-drawn northern twilight set in, the submarine's opportunity would arrive. The Russian ships were resisting fiercely. Occasionally a German battleship would fall out of line, more or less damaged. The destroyers of the Republic, too, were far from inactive. On four separate occasions groups of them made desperate "hussar strokes" upon their powerful foes. In each case the plucky boats were sent to the bottom under a heavy concentrated fire, but not before their torpedoes had "got home" against the enormous hulls of their opponents. Suddenly a rain-squall swept the sea, blotting out the light-grey hulls of the German ships. It was Stockdale's chance, and he took it. "Action stations! Launch home all tubes!" Under the hail-swept waves R19 plunged, submerged to 18 feet, and headed straight for the centre of the enemy division. CHAPTER XVII Hit With the tips of her periscopes just showing above the surface, R19 stealthily approached her prey. Every water-tight door was closed, even the hatch between the conning-tower and the centre compartment. Within the confined space of the conning-tower stood the Hon. Derek, Fordyce, and Petty Officer Chalmers, whose duty it was to transmit the Lieutenant-Commander's orders by means of voice-tubes, and telegraph to the torpedo-hands, engine-room artificers, and men stationed at the auxiliary ballast-tanks. The hail and spray beating upon the glass lenses of the periscopes blurred and distorted the images in the object-bowls. There was no time for the globules of moisture to fall clear of the prepared glass before others took their place. Fumes of so-called smokeless powder, too, were drifting sluggishly to leeward, beaten down by the heavy fall of rain. In the circumstances, it made the chances of the slender periscopes being seen very remote, while, on the other hand, although not to the same extent, the submarine's intended victims were obscured by the misty conditions. Twice R19 dived deeply as groups of torpedo-boats tore athwart her track, ignorant of the presence of the formidable British submarine. Then, cautiously and deliberately rising towards the surface, R19 again exposed her periscopes. "Thanks be!" ejaculated the Hon. Derek, as, a couple of points on the starboard bow, loomed up the towering outlines of one of Germany's most recent battleships. A slight touch of the helm and the submarine turned until her bow-tubes pointed dead on the stem of her prey. At the rate the battleship was moving she would be struck amidships by the time the two torpedoes covered the intervening space. "Fire!"