1903-07

Shackleton left The Discovery on 28 February 1902 to cheers from her crew, and set off on Morning for Lyttleton, New Zealand. In mid-June 1903, he returned to London to a good reception, particularly from Sir John Murray, president of the Royal Scottish Geographical Society, and Sir Joseph Hooker, a surgeon from an earlier expedition to the Antarctic. They presented him as the first praiseworthy person to return from the Discovery Expedition. Additionally, Shackleton noticed that Londoners had an unquenchable desire for his tales of the Antarctic, which helped him lay the groundwork for further expeditions.

In search of regular employment, Shackleton applied for a commission in the Royal Navy but despite the sponsorship of Sir Clements Markham, President of the Royal Geographical Society and President of the Royal Society, he was not successful. With Markham's blessing, he accepted a temporary post assisting the outfitting of the Terra Novaa for the second Discovery relief operation but turned down the offer to sail with her as chief officer. However, he was offered, and accepted, the secretaryship with the Royal Scottish Geographical Society. He was searching for an office job in order to be able to marry 35-year-old Emily Mary Dorman, with whom he shared a love of literature, particularly Robert Browning. He married Dorman on 9 April 1904, with the marriage producing three children: the youngest, Edward, became the first westerner to climb Mount Mulu in Borneo. Shackleton wrote long letters to his wife during his explorations, but also engaged in several extramarital affairs, including one with the American actress Rosalind Chetwynd.

Shackleton was active in organizing an Antarctic relief mission with the Argentine government and arranging troop transportation for the Russians. In 1906, Shackleton ventured into politics, supporting the Liberal Unionist Party and unsuccessfully standing for Parliament in the 1906 general election in Dundee, garnering 3,865 votes to the victor's 9,276. At the same time, Shackleton was preparing for another expedition to the Antarctic by raising funds and thus was active as a mill promoter and in business ventures such as a tobacco company. The mill owner, William Beardmore, was impressed with Shackleton and helped sponsor his next expedition. Shackleton also used his connections with wealthy friends to raise capital, and subsequently convinced Sir Phillip Lee Brocklehurst and author Campbell Mackellar to finance his expedition. With funds attained, Shackleton presented his idea for an Antarctic expedition to the Royal Geographic Society in competition with a proposal from Henryk Arctowski. Shackleton's project was chosen, and on 12 February 1907, the details of the voyage, named the British Imperial Antarctic Expedition, were published in the Royal Society's newsletter, Geographic Journal.