During a subsequent confrontation with thirteen Japanese aircraft on 1 December, Armidale was struck by two torpedoes and a bomb, and began to sink; the order to abandon ship was given. After helping to free a life-raft, Sheean was wounded by two bullets. He made his way to the aft Oerlikon 20 mm cannon and began to fire on the Japanese aircraft to protect those in the water. Sheean managed to shoot down one of the Japanese bombers, but was killed when Armidale sank. Many of the survivors credited their lives to Sheean and he was posthumously mentioned in despatches. In 1999, the submarine HMAS Sheean was named in his honour, and efforts have been made to have Sheean belatedly awarded the Victoria Cross for Australia.
Sheean was born in Lower Barrington, Tasmania, on 28 December 1923, the youngest of fourteen children to James Sheean, a labourer, and his wife Mary Jane (née Broomhall). Soon after his birth, the Sheean family moved to Latrobe, where he was educated at the local Catholic school. Following the completion of his schooling, Sheean gained casual employment working on several farms in the vicinity of Latrobe and Merseylea.
On 21 April 1941, Sheean enlisted in the Royal Australian Naval Reserve. He had followed in the steps of five of his brothers who had already joined the armed forces—four in the Australian Army and one in the Royal Australian Navy—for service in the Second World War. Sheean was initially posted to the Hobart naval base HMAS Derwent for training, where he gained a period of seafaring experience aboard HMAS Coombar, an auxiliary minesweeper, from 17–31 December. On finishing his initial training course, Sheean was attached to the Flinders Naval Depot in Western Port, Victoria, for further instruction from 11 February 1942.
Completing his course at the Flinders Naval Depot, Sheean was posted to the Garden Island naval base HMAS Penguin in Sydney Harbour on 11 May. During his time with Penguin, he was billeted on the requisitioned ferry HMAS Kuttabul. Granted a period of leave later that month, he returned home to Tasmania. While he was on leave, Japanese midget submarines attacked Sydney Harbour and sank Kuttabul on 31 May. Returning to Sydney eleven days after the raid, Sheean joined the newly commissioned Bathurst-class corvette HMAS Armidale as an Oerlikon anti-aircraft gun loader.
Leaving Sydney Harbour in late August 1942, Sheean served aboard Armidale as she carried out "relatively uneventful" escort duties along the North Queensland, Port Moresby and Milne Bay coasts over the subsequent two months. During October, Armidale was ordered to Darwin. Setting sail, she arrived on 7 November and was detailed to assist in the Australian operations in Timor.
On 24 November 1942, the evacuation of the 2/2nd Australian Independent Company from Timor along with 150 Portuguese people was approved by the Allied Land Forces Headquarters. In response to this, Commodore Cuthbert Pope, the Naval Officer-in-Charge Darwin, organised an operation utilizing HMA Ships Kuru, Castlemaine and Armidale. The operation was to involve the three ships undertaking two voyages each, the first to take place on the night of 30 November/1 December and involve a trip to Betano, Timor, in which the ships were to land 50 fresh Dutch guerrillas in the area along with supplies, and simultaneously withdraw 190 Dutch soldiers as well as the 150 Portuguese refugees. The second excursion was to be carried out on the night of 4/5 December, and entail the extraction of the 2/2nd Independent Company.
At 22:30 on 28 November 1942, Kuru set sail for Betano. Kuru was scheduled to arrive at approximately 20:30 on 30 November, where she was to unload the supplies on board and embark the Portuguese refugees, which were to transfer to Castlemaine once she arrived along with Armidale two hours later. However, Kuru hit bad weather during her voyage and arrived at Betano three hours late. Armidale—with two Dutch Army officers, 61 Netherlands East Indies troops and three Australian Army soldiers aboard—and Castlemaine set sail from Darwin at 01:42 on 29 November. At approximately 09:15 on 30 November, while 190 kilometres (100 nmi) from their destination, the two ships were attacked by a single Japanese aircraft. Having missed with several bombs, the aircraft flew off in the direction of Timor an hour later. Fearing that their discovery by this aircraft would jeopardise the mission, Castlemaine's Commanding Officer, Lieutenant Commander Philip Sullivan, ordered evasive action and signalled Darwin for further orders. A signal returned decreeing that the operation must proceed and a party of fighter aircraft were to be dispatched as protective cover.
Continuing in their voyage, Armidale and Castlemaine were attacked twice more by air, each time by a formation of bombers that bombed and machine-gunned the ships. Despite this, neither ship suffered damage or casualties and both arrived at Betano at 03:30 on 1 December, however there was no sign of Kuru. Having made sure that Kuru was not in the bay, the two corvettes decided to abandon the mission and sailed south in order to return to Darwin. Kuru's commanding officer, Lieutenant John Grant, had loaded 77 of the Portuguese refugees as well as one critically injured Australian soldier on board the ship and set sail at around 02:00 on 1 December from Betano, fearing he had missed the rendezvous with the other two ships. While approximately 110 kilometres (59 nmi) south of Betano, Armidale and Castlemaine sighted Kuru, and the three ships closed by dawn.
Following the transfer of passengers from Kuru to Castlemaine, the former received orders that she was to return to Betano that evening "and do the job tonight". At this time, a formation of Japanese aircraft was spotted and Kuru sailed for cover. Assessing the situation, Sullivan—as senior officer—decided that Armidale would accompany Kuru in order to unload the former's passengers at Betano while Castlemaine returned to Darwin. Armidale and Kuru assumed separate routes to Betano, and at approximately 13:00 Armidale was attacked by a party of five Japanese bombers; the explosives, however, fell wide of their target. At 13:58, Armidale reported that she was under attack from "nine bombers, four fighters" over the Arafura Sea.
Armidale undertook evasive action, manoeuvring frantically to avoid the aerial attack. However, at 15:15, the vessel was struck by two air-launched torpedoes, one hitting her port side and the other colliding with the engineering spaces, before a bomb exploded aft. Armidale listed sharply to port at this stage, and the order was given to abandon ship. As the crew leapt into the sea, they were strafed by the attacking aircraft. Sheean—after assisting to free a life-raft—was hit by two bullets from one of the aircraft, wounding him in the chest and back. Scrambling across the deck, he strapped himself into the aft Oerlikon 20 mm cannon and began shooting at the fighters in an effort to protect some of the sailors already in the sea. Subject to the fire from Sheean's Oerlikon, the Japanese aircraft were kept at bay and were unable to effectively strafe those in the water.
With Armidale rapidly sinking, Sheean continued to fire and managed to shoot down one of the Japanese bombers. He damaged a further two aircraft before Armidale's stern was engulfed by the sea. Despite this, Sheean maintained his fire as the water rose above his feet, and remained firing as he "disappeared beneath the waves". Sheean's crewmates later testified to witnessing tracers rising from beneath the water's surface as Sheean was dragged under.
Sheean was among 100 of the original 149 people on board HMAS Armidale at the time of the attack who were killed during the ship's sinking and its aftermath. Many of the survivors attributed their lives to Sheean. For his "bravery and devotion when HMAS Armidale was lost", Sheean's actions were recognised with a posthumous Mention in Despatches, awarded on the recommendation of Armidale's commanding officer, Lieutenant Commander David Richards, and announced in a supplement to The London Gazette on 29 June 1943. However, many hold the opinion that Sheean's gallantry, devotion to duty and self-sacrifice were worthy of the Victoria Cross, with author Robert Macklin stating his "actions were in the highest tradition of the Australian military" and comparing them with those of Vietnam War Victoria Cross recipient Kevin Wheatley.
On 1 May 1999, the submarine HMAS Sheean was launched by Ivy Hayes—sister of Teddy Sheean—named in the ordinary seaman's honour. Sheean was subsequently commissioned into the Royal Australian Navy on 23 February 2001, and was the first Royal Australian Navy vessel to be named in honour of a naval rating. Carrying the motto "Fight On", the vessel was one of six Collins-class submarines entered into service. Later that year, a Bill was introduced into the Australian Senate to have three awards of the Victoria Cross for Australia made, one being to Sheean. The Bill came as part of a campaign by the then-leader of the Australian Labor Party and Federal Opposition, Kim Beazley, to secure more rights for war veterans. However, it was subsequently rejected by the Liberal Government. A painting depicting Sheean's final moments is held by the Australian War Memorial. His home town of Latrobe commemorates his life via the Sheean Walk and Teddy Sheean Memorial, opened in 1992. In 2003, the Australian Navy Cadets established a training ship at Tewantin, Queensland, called NTS Sheean in his honour.
In 2011, at the direction of the Parliamentary Secretary for Defence, Senator David Feeney, the Defence Honours and Awards Appeals Tribunal opened an inquiry into thirteen cases of unresolved recognition for past acts of gallantry. Among the group were eleven naval personnel, including Sheean. Known as the 'Valour Inquiry', the Tribunal was directed to determine if the individuals were unduly overlooked for recognition at the time of their actions and, if so, whether retrospective awards were appropriate. The inquiry lasted two years and witnessed 166 written submissions from the public, before the Tribunal reported its findings in January 2013. In the case of Sheean, the Tribunal found that there was no manifest injustice with the award of the Mention in Despatches, and that there was no new evidence to support the reconsideration of Sheean for a Victoria Cross for Australia. If Sheean had lived, they reported, he might have been recommended for either the Conspicuous Gallantry Medal or the Distinguished Service Medal instead, but neither medal could be awarded posthumously in 1942. The Tribunal did recommend that the RAN perpetuate the use of Sheean as the name of a major combatant vessel.