In March 1917, the ss. _Osmanieh_, 4,440 tons gross, owned by the Khedivial Mail Company, but chartered by the Admiralty, was on passage from Malta to Madras when, at about 5.40 P.M., a hostile submarine was sighted. The ship was commanded by Lieutenant Mason, R.N.R., and was flying the White Ensign; she was zigzagging, and was escorted by a single destroyer, the _Racoon_, Lieutenant-Commander Kenneth F. Sworder, R.N. The weather was fine, the sea calm, and visibility good--about eight or nine miles. The submarine when sighted was about 1,500 yards distant, and two or three points on the _Osmanieh’s_ starboard bow. Only six feet of her length was visible, and she appeared to be drifting; puffs of blue-grey vapour were coming from her, which seemed to hang in the air and float away without disappearing. When nearer--at 800 to 1,000 yards--she was seen to be moving, for a ‘feather’ was visible as well as the vapour. The _Osmanieh’s_ head was put two points to starboard to steer for the submarine; but as it changed position rapidly, helm was put hard a-port, the whistle was blown to draw the escort’s attention, and the alarm gong was sounded. The ship then opened fire with her two guns. The second round from the after gun appeared to score a hit; but the U-boat was at that time almost astern and shining brightly in the sun, so that it was not possible to observe with certainty. _Racoon_, when _Osmanieh_ opened fire, was ahead of her, on the port bow and going 16½ knots; but the moment the guns were heard, Lieutenant-Commander Sworder increased speed to 23 knots, put his helm hard a-port, and sighted the U-boat. It had at first ‘the appearance of a calcium light giving off intermittent puffs of smoke’; but when the ship’s head was turned towards it, a periscope and distinct feather were seen, as the submarine came out of the trough of the swell. The manœuvre which followed was a very skilful and effective one. _Racoon_ came to meet _Osmanieh_, who had now turned sixteen points to starboard and was on the other side of the submarine and overhauling her. _Osmanieh_ continued firing till she saw her escort only 400 yards from the target. She had intended to try a depth-charge herself, and as soon as she passed the U-boat she had stopped her port propeller for this purpose, hoping to get the ship’s stern back into or near the enemy’s course; but she now gave this up and turned sharply away to port. As she did so, _Racoon_ crossed her stern at full speed, and immediately saw the submarine on her own starboard side, the periscope just showing about five yards off and moving almost directly to meet her. Those on the destroyer’s deck had a glimpse of about ten feet of a grey hull with green and rust-coloured marks showing; then, as the ship passed over this, she dropped her starboard depth-charge, set to eighty feet, turned swiftly to port and dropped her port depth-charge, four seconds after the first.