In due course R19 arrived off the Gulf of Riga. During the run across the Baltic she had studiously avoided craft of every description, although she had several chances of successfully attacking small German vessels. Stockdale let them "carry on", not from choice but of necessity. A tremendous lot depended upon the secret arrival of a British submarine to help the Russian navy against that of the Huns. He acted upon the principle that a hunter stalking a lion will not waste a shot upon a jackal, and thus prematurely alarm the main object of his efforts. Just before midnight R19 rose to the surface and lay motionless upon the tranquil water. She was now within sight and sound of the guns, for the German land force had thrown the Russians out of the important town of Riga, while their auxiliary vessels were busily engaged in sweeping the mine-field across the mouth of the gulf, to enable the High Seas Fleet to find a secure anchorage before attempting to discover and overwhelm the New Republic's Baltic Fleet. Away to the south-eastward, and faintly discernible against the continuous flashes of the guns, could be seen the German mine-sweepers and their covering vessels--light cruisers and torpedo-boats. As yet the battleships and armoured cruisers had not left Kiel. For an hour R19 remained motionless; then the order was given to dive and rest on the sea bed. The reason no one on board knew except the Hon. Derek and Lieutenant Macquare. The men could not form any satisfactory opinion of the submarine's apparent inactivity. They could not understand why they did not go for everything afloat that was German, instead of "sounding" time after time. For three successive nights R19 popped up for the space of sixty minutes. Each time the officers carefully fixed the submarine's position by means of cross bearings and the use of position-finders. At midnight on the fourth consecutive night of inaction Fordyce and the Lieutenant-Commander were on deck when they heard the subdued hum of an aerial propeller. It lacked the well-known sound of a British machine, nor did it make a noise like a Gotha. The two men exchanged glances. "That's it!" exclaimed the Hon. Derek. "Pass the word for the Very's light." It seemed a risky thing to do--to send up a couple of rockets from a British craft that was lying four or five miles only from the line of German patrol-boats--but there was no option. A red and a green rocket blazed overhead. From the hovering sea-plane came an answering flash. Her motors were then switched off, and, with a swift volplane, she alighted upon the surface at less than fifty yards from the submarine. Then "taxi-ing" cautiously, the sea-plane approached the lee'ard side of R19, until one of the occupants dexterously caught a rope hurled from the submarine's deck. A greatcoated, muffled figure made its way along one of the projecting floats of the sea-plane and clambered up the bulging side of R19.