Suddenly came the cry, "Submarine!" Sub-chaser 129 had sighted the moving feather of a U-boat about 1,600 yards off her port quarter. Signaling to S. C. 215, S. C. 129 altered her course to the left to deliver an attack at right angles. The U-boat was heading south, apparently getting in position to attack the bombarding forces. In a moment a second feather was sighted a little farther to westward. As S. C. 129 reached the supposed path of the undersea boat, a depth-bomb was dropped. When it exploded, the enemy submerged for almost a minute, and then reappeared, showing both periscopes. S. C. 129 immediately began laying a pattern of depth-charges ahead of the U-boat and at right angles to his course. When the seventh bomb exploded, in the water thrown up objects resembling pieces of metal appeared, and there was another explosion, seemingly in the submarine. The chaser crew was confident that submarine was destroyed. Sub-chaser 215, sighting another periscope 750 yards away, opened fire with her three-inch gun and port machine-gun, hoisting signal to form for attack. The second three-inch shot dropped within two feet of the periscope, the commanding officer reported, and shattered it, a column of water six feet high rising into the air. The U-boat seemed to be turning sharply to starboard in the direction of the British light cruisers, which were then entering their bombarding sector. S. C. 215 and S. C. 128 closed in on the submarine and laid a pattern of depth-charges. As the fourth charge exploded, the executive officer of S. C. 215 sang out, "That got him!" He had seen what appeared to be a ship's plate and debris rise to the surface and then disappear. Heavy oil rose, covering the water in the vicinity, and the chaser crews concluded the U-boat had been sunk. S. C. 215 and S. C. 128 then turned and headed for S. C. 129, which had first reported sighting a "sub," but which was lying to, repairing her engines. The unit stood over to capture the Austrian hospital ship, hoisting the international flag, "Stop instantly!" The British cruisers _Nereide_ and _Ruby_ were, at the time, astern of the Austrian vessel, and the _Nereide_ signaled that she would stop and take off the armed guard crew if the chasers wished to take over the hospital ship. The chasers, which were north of the Austrian port, replied that they would take her over when clear of Durazzo. The little American craft took charge of the big Austrian vessel, the British cruisers _Tribune_ and _Shark_, signaling, "Go to Brindisi." Reaching Brindisi, they released the hospital ship, which had been taken to port for investigation. Then, with a sense of duty well done, the chasers dropped anchor in the harbor, and "called it a day."