The fifth patrol took place between 2 and 7 November 1941, and it is the patrol when the only attack of Delfinul took place. Its mission was to attack the convoys destined for Sevastopol. Its CO was Constantin Costăchescu. Near Constanţa they spotted an enemy submarine, but because of the darkness, they lost it. On the morning of 5 November, the submarine reached the neighboring waters of Yalta. At 6:36, they spotted a patrol vessel and kept watch. Around 8:05, sub-lieutenant Constantin Stegaru spotted a large transport vessel on a course of 290, steaming for Yalta. At 8:15, the ship turned to the left, closing on the submarine. The CO decided to wait for the ship to pass behind him and shot from an aft tube. At 8:43, Delfinul launched a torpedo from tube 6, from away. The torpedo explosion, followed by a bigger one, could be heard, moments after the launch. It is possible that the ship was not escorted because the first contact with a submarine hunter ship came an hour after the attack. The depth charging lasted from 10:30 until 18:30 (6:30 pm). There were 23 passes and 80 to 90 explosions from depth charges. During the attack, Căpitan (USN rank - Lieutenant) Constantin Costăchescu dove the submarine deeper and deeper, and when the enemy was listening, he would stop the submarine's machinery. Afterwards, they went near the Turkish coast, but a dreadful storm made the trip home a difficult venture. Căpitan (USN rank - Lieutenant) Constantin Costăchescu was later awarded the Order of Michael the Brave 3rd Class for the attack. The alleged sunken Soviet ship was claimed to be the 1,975-ton cargo Uralets (also known as Uralles).Antony Preston, Warship 2001-2002, Conway Maritime Press, 2001. p. 76Richard Compton-Hall, Submarines at War 1939-1945, Periscope Publishing, 2004, p. 127 However, according to modern evaluations, the ship was sunk by the Luftwaffe on 30 October, during an air raid on Yevpatoria, and the torpedo attack missed the minelayer Ostrovsky Morozov M. E, The air battle for Sevastopol, 1941-1942, Eksmo Publishing, 2007, p. 147 The latter claim, however, is highly unlikely, as the crew of Delfinul reported to have heard an explosion seconds after launching the torpedo. The struck ship was most likely the Soviet tanker Kreml, which was damaged.Donald A Bertke, Gordon Smith, Don Kindell, World War II Sea War, Volume 4: Germany Sends Russia to the Allies, p. 389Florian Bichir, Corsarii uitați ai adâncurilor, p. 101 (in Romanian)Ships hit by U-boats: Kreml’, Soviet Motor tanker
