As a leader of the Nimrod Expedition, Shackleton was seen as a rival to Robert Falcon Scott's Discovery Expedition in what became a period known as the Heroic Age of Antarctic Exploration. In January 1909, Shackleton made it farthest south than anyone had before.

His next project saw him attempt to cross the Antarctic by sea from pole to pole, but his ship Endurance became stuck in pack ice and was crushed. Shackleton kept his crew together and miraculously no lives were lost, making him one of the true heroes of the era.