Ernest Shackleton and five men of the Imperial Trans-Antarctic Expedition launch a lifeboat from uninhabited Elephant Island in the Southern Ocean to organise a rescue for the crew of the sunken Endurance.

The Imperial Trans-Antarctic expedition of 19141917 is considered to be the last major expedition of the Heroic Age of Antarctic Exploration. Conceived by Sir Ernest Shackleton, the expedition was an attempt to make the first land crossing of the Antarctic continent. After Roald Amundsen's South Pole expedition in 1911, this crossing remained, in Shackleton's words, the "one great main object of Antarctic journeyings". Shackleton's expedition failed to accomplish this objective, but became recognized instead as an epic feat of endurance.

Shackleton had served in the Antarctic on the Discovery expedition of 19011904, and had led the Nimrod expedition of 19071909. In this new venture he proposed to sail to the Weddell Sea and to land a shore party near Vahsel Bay, in preparation for a transcontinental march via the South Pole to the Ross Sea. A supporting group, the Ross Sea party, would meanwhile establish camp in McMurdo Sound, and from there lay a series of supply depots across the Ross Ice Shelf to the foot of the Beardmore Glacier. These depots would be essential for the transcontinental party's survival, as the group would not be able to carry enough provisions for the entire crossing. The expedition required two ships: Endurance under Shackleton for the Weddell Sea party, and Aurora, under Aeneas Mackintosh, for the Ross Sea party.

Endurance became beset in the ice of the Weddell Sea before reaching Vahsel Bay, and drifted northward, held in the pack ice, throughout the Antarctic winter of 1915. Eventually the ship was crushed and sank, stranding its 28-man complement on the ice. After months spent in makeshift camps as the ice continued its northwards drift, the party took to the lifeboats to reach the inhospitable, uninhabited Elephant Island. Shackleton and five others then made an 800-mile (1,300 km) open-boat journey in the James Caird to reach South Georgia. From there, Shackleton was eventually able to mount a rescue of the men waiting on Elephant Island and bring them home without loss of life. The remarkably-preserved wreck of Endurance was discovered on the seafloor in 2022.On the other side of the continent, the Ross Sea party overcame great hardships to fulfill its mission. Aurora was blown from her moorings during a gale and was unable to return, leaving the shore party stranded without proper supplies or equipment. Nevertheless, the depots were laid, but three lives were lost before the party's eventual rescue.

Sir Ernest Henry Shackleton (15 February 1874 – 5 January 1922) was an Anglo-Irish Antarctic explorer who led three British expeditions to the Antarctic. He was one of the principal figures of the period known as the Heroic Age of Antarctic Exploration.

Born in Kilkea, County Kildare, Ireland, Shackleton and his Anglo-Irish family moved to Sydenham in suburban south London when he was ten. Shackleton's first experience of the polar regions was as third officer on Captain Robert Falcon Scott's Discovery expedition of 1901–1904, from which he was sent home early on health grounds, after he and his companions Scott and Edward Adrian Wilson set a new southern record by marching to latitude 82°S. During the Nimrod expedition of 1907–1909, he and three companions established a new record Farthest South latitude at 88°S, only 97 geographical miles (112 statute miles or 180 kilometres) from the South Pole, the largest advance to the pole in exploration history. Also, members of his team climbed Mount Erebus, the most active Antarctic volcano. For these achievements, Shackleton was knighted by King Edward VII on his return home.

After the race to the South Pole ended in December 1911, with Roald Amundsen's conquest, Shackleton turned his attention to the crossing of Antarctica from sea to sea, via the pole. To this end, he made preparations for what became the Imperial Trans-Antarctic Expedition, 1914–1917. Disaster struck this expedition when its ship, Endurance, became trapped in pack ice and was slowly crushed before the shore parties could be landed. The crew escaped by camping on the sea ice until it disintegrated, then by launching the lifeboats to reach Elephant Island and ultimately South Georgia Island, a stormy ocean voyage of 720 nautical miles (1,330 km; 830 mi) and Shackleton's most famous exploit. In 1921, he returned to the Antarctic with the Shackleton–Rowett Expedition, but died of a heart attack while his ship was moored in South Georgia. At his wife's request, he was buried there. The wreck of Endurance was discovered just over a century later.Away from his expeditions, Shackleton's life was generally restless and unfulfilled. In his search for rapid pathways to wealth and security, he launched business ventures which failed to prosper, and he died heavily in debt. Upon his death, he was lauded in the press but was thereafter largely forgotten, while the heroic reputation of his rival Scott was sustained for many decades. Later in the 20th century, Shackleton was "rediscovered", and became a role model for leadership in extreme circumstances.In his 1956 address to the British Science Association, Sir Raymond Priestley, one of his contemporaries, said "Scott for scientific method, Amundsen for speed and efficiency but when disaster strikes and all hope is gone, get down on your knees and pray for Shackleton", paraphrasing what Apsley Cherry-Garrard had written in a preface to his 1922 memoir The Worst Journey in the World. In 2002, Shackleton was voted eleventh in a BBC poll of the 100 Greatest Britons.