ANZAC - Captain Otto von Hersing and the U-21 arrived off Anzac just after noon on 25 May and immediately began stalking HMS Triumph. As they did so he coolly evading the accompanying destroyer HMS Chelmer. "A huge cloud of smoke leaped out of the sea. In the conning tower we heard first a dry, metallic concussion and then a terrible, reverberating explosion. It was a fascinating and appalling sight to see, and I yearned with every fibre to keep on watching the fearful picture; but I had already seen just about enough to cost us our lives."

"We dived to seventy feet and headed toward the monster, passing far below the lines of patrol craft. Their propellers, as they ran above us, sounded a steady hum. For four and a half hours after I caught sight of the ship I manoeuvred the U-21 for a torpedo shot, moving here and there and showing the periscope on the smooth surface of the sea for only the briefest moments. In the conning tower my watch officer and I stood with bated breath. We were groping toward a deadly position - deadly for the magnificent giant of war on the surface above. "Out periscope!" HMS Triumph stood in formidable majesty, broadside to us, and only 300 yards away. "Torpedo - fire!" My heart gave a great leap as I called the command. And now one of those fearfully still, eventless moments. Suspense and eagerness held me in an iron grip. Heedless of all else, I left the periscope out. There! And I saw the telltale streak of white foam darting through the water. It headed swiftly away from the point where we lay, and headed-straight - yes, straight and true."

He scored a direct hit and the Triumph bagan to sink. Trawlers and destroyers raced towards the Triumph to pick up the survivors that were bobbing about all over the surface of the sea. The speed of their response meant that they only lost some 73 men. Meanwhile Captain Otto Hersing was desperately trying to escape the scene. 

"A huge cloud of smoke leaped out of the sea. In the conning tower we heard first a dry, metallic concussion and then a terrible, reverberating explosion. It was a fascinating and appalling sight to see, and I yearned with every fibre to keep on watching the fearful picture; but I had already seen just about enough to cost us our lives. The moment that dread white wake of the torpedo was seen on the surface of the water, the destroyers were after me. They came rushing from every direction. "In periscope!" And down we went. I could hear nothing but the sound of propellers above me, on the right and on the left. Why hadn't I dived the moment after the torpedo left? The two seconds I had lost were like years now. With that swarm converging right over our heads, it surely seemed as if we were doomed. Then a flash crossed my brain. "Full speed ahead," I called, and ahead we went right along the course the torpedo had taken, straight toward the huge craft we had hit. It was foolhardy, I admit, but I had to risk it. Diving as deeply as we dared, we shot right under the sinking battleship. It might have come roaring down on our heads - the torpedo had hit so fair that I rather expected it would. And then the U-boat and its huge prey would have gone down together in an embrace of death. That crazy manoeuvre saved us. I could hear the propellers of destroyers whirring above us, but they were hurrying to the place where we had been."

ANZAC - By mid-May the German submarines which had been despatched to the eastern Mediterranean were to arriving in the Eastern Mediterranean. Of these the most effective would be the U21, under the command of Lieutenant Commander Otto Hershing, which had set off from the German naval port of Wilhelmshaven on 25 April. En route she was spotted many times and in anticipation of her arrival off the Gallipoli beaches anti-submarine precautions were adopted.

On 17 May the number of battleships lying off Helles was reduced from seven to four and at Anzac the number was halved to only two. In the remaining ships a diligent anti-submarine watch was kept, anti torpedo nets were hung out and escorting destroyers tried to keep the U Boats away from their prey. The U21 reached Gallipoli on 25 May and went straight into action. At first the anti-submarine defences seemed to work. Destroyers spotted her periscope and prevented an attack on the HMS Swiftsure off Helles, whiled a torpedo fired at HMS Vengeance was spotted and successful avoiding action taken. Moving north a new target in the form of the HMS Triumph was stalked off Anzac. At 12.25 U21 struck and although the torpedo was spotted it was too late. Ordonary Seaman W. G. Northcott recalled events in his interview for the BBC Great War series recorded back in 1963.

"I was range finder up in the aloft position. One day midday I came down to get my ration of rum. I'd just drunk it when I heard a lot of commotion, guns firing, so I immediately returned to my position. On my way up a torpedo struck us. Then when I did get up I saw one of our boys aiming his rifle at a torpedo coming through the water. Unfortunately he missed but he stuck to his post firing at this torpedo trying to divert it. No luck so it came through and hit us. We didn't know that the Germans had invented a net cutter on the front of the torpedo. We were protected by huge steel nets pushed out on booms to try and stop the torpedos. But they just passed straight through and hit us. I could feel the ship listing over. Remembering I had a brand new pair of boots on which I'd bought the previous day I took them off and hung them on the rigging thinking to myself that if nothing happened they'd still be there and I came down the rigging. By this time the ship was heeled pretty bad and the majority of the ratings were catching hold of the nets, the leeside, the side in the water. I didn't like the idea, I don't know why, and I jumped off and got in the water, Shortly after the destroyer Chelmer came up and started picking us out. Then she put her bows on the stern of the ship which by now had heeled almost on one side. A lot of the men got on board of her that way." (Ordinary Seaman W. G. Northcott, HMS Triumph)

As a result of England's skilful handling of HMS Chelmer only 75 men from the Triumph were lost. The arrival of the German submarines changed the whole situation for the British supporting fleet. The loss of the Triumph caused the emergency withdrawal of all the remaining battleships to the protected anchorage of Imbros.