I would nominate the HMS Breconshire, the supply ship that made it through to Malta during that islands darkest hour. Pounded to the point of sinking, with most of her crew dead or woulnded, her Captain and the convoy escorts assisting her, refused to give up.
I attach the following history of this most gallant and influential ships in history. perhaps not the the most impressive, but her survival can be said to hav influecned the outcome of a campaign....
BRECONSHIRE (1) was built in 1939 by Taikoo Dk Engineering Co. at Hong Kong with a tonnage of 9776grt, a length of 507ft, a beam of 66ft 3 in and a service speed of 18 knots. On completion she was acquired by the Admiralty and converted into an Auxiliary Supply Ship and commissioned as HMS Breconshire. On 15th April she ran into Malta supported by Admiral Cunningham's naval strength and an enemy attack on this fleet enable a number of empty merchantmen to to make a break for Alexandria. Between 21st-26th July she participated in 'Operation Substance' when a convoy of six ships fought through to Malta allowing the Breconshire and six empty cargo ships to escape eastwards. In all, HMS Breconshire made more trips to Malta than any other merchantman. Ensuring the survival of Malta was vital and every effort was made to keep the island supplied, so much so, that on 17th December 1941 three cruisers and fourteen destroyers were deployed to ensure that the Breconshire got through. However, in March 1942, under the command of Capt. Colin Hutchinson RN, she was to fight her last battle. She left Alexandria on 20th March, as commodore ship, with a cargo mainly consisting of high explosive and kerosene, accompanied by Clan Campbell (Clan Line), Pampas (Buries Marks) and the Talabot (Wilhelmsen). The next day, by which time the Clan Campbell was straggling, the convoy was met by Admiral Vian on HMS Cleopatra, three other cruiser and 16 destroyers. Aircraft provided overhead cover and three submarines were patrolling to the north. On the 22nd there were several ineffective attacks by Italian Savoia bombers but HM submarine P 36 reported heavy Italian surface fleet steaming to intercept. At 13.30 an aircraft dropped a line of flares to guide the Italian force towards the convoy and with them began the Battle of Sirte Gulf. Six destroyers and the anti-aircraft cruiser HMS Carlisle were delegated to protect the convoy while the remainder of the escort steamed off to meet the oncoming Italians. Although a smoke screen was laid to screen the merchantmen bombing had started by mid-afternoon and was continuous with all the ships being straddled but, fortunately, not hit. By late-afternoon the Italian cruiser Littorio, three cruisers and twelve destroyers arrived on the scene and the convoy was ordered to alter course, southward, into the Sirte Gulf. Laying a smoke screen Vian's fleet went after the Italians whose objective was to get round the smoke to get a clear shot at the convoy. As they broke through Vian's cruiser fired a broadside of torpedoes which caused the Italians to turn away. The manoeuvre was repeated but after another broadside was fired the Italians withdrew and the battle was over. However, by now the merchantmen were so far south that they could not possibly reach Malta, some 240 miles away, under the cover of darkness. As the main escort no longer had the fuel or ammunition to provide effective cover Vian ordered the merchantmen to break convoy and head for Grand Harbour, Valetta at full speed. The Breconshire set off at 17 knots accompanied by the destroyers HMS Southwold and HMS Beaufort and the A.A. cruiser Carlisle and by daybreak they were only 20 miles from home. But enemy aircraft were already circling waiting to attack. Air support was requested but nothing was available to cover the ships as they approached Malta. On 23rd March a single Junkers 88 commenced the first attack which was followed by Me 109 fighter bombers who scored three hits. The Ju 88's returned at regular intervals scoring more hits by which time Breconshire was lying dead in the water, 10 miles from Malta. The cruiser, HMS Penelope left Valetta Harbour to take the ship in tow but twenty feet waves caused the tow to part leaving her to drift towards the protective minefields. By noon she managed to anchor short of the minefields and two cruiser and four destroyers gave her anti-aircraft protection. During the following night the anchors dragged and the mines were close enough to be clearly visible from the ship. HMS Southwold managed to get a tow line aboard but in doing so hit a mine and broke her back finally sinking later that day. The air attacks recommenced but the Breconshire was not hit and by midnight the weather abated sufficiently to allow HM tugs Ancient and Robust to reach the stricken ship. At 2.00 am on the 25th she was under tow but a strong wind prevented entry into Grand Harbour so it was decided to put her in Marsaxlokk Bay. As the ship turned the swell caused her to veer madly. Breconshire signalled the Ancient 'I have a strong tendency to come up into wind', to which Ancient replied 'You're telling me!' At 10.00 Breconshire entered the bay and moored to No.1 buoy and her exhausted crew were taken off for some well earned rest. The tanker HMS Plumleaf was delegated to go alongside and take off the kerosene and fuel oil but this could not be done until the tanks were freed and opened. While this was being done HMS Plumleaf was bombed and beached. The Luftwaffe, being determined to destroy the three merchantmen who made it, increased their air attacks with the Pampas and the Talabot being rendered unrecognisable and Breconshire being repeatedly dive bombed. On 26th March hasty repairs were commenced so that she could be towed into Grand Harbour. The air attacks resumed and at 18.30 a lone Ju 88 scored four direct hits which caused a fire that was quickly brought under control. Miraculously the ship did not explode but she was settling and listing to port and by sunset the port rail was under water. At daybreak on the 27th she was still afloat but fires had again broken out, abaft the No.3 hold was a blazing inferno and ammunition was beginning to explode. The Captain and fourteen officers went out to her by launch but attempts to scuttle her fail because of the intensive heat. Moments after Capt. Hutchinson slid off the ship she rolled on her side and then capsized. In April 1954 she was raised and, upside down, towed to Trieste where, after examination to see if repair was possible, she was broken up.