In 1914, McIlroy, along with
Alexander Macklin, were the two physicians assigned under Shackleton on 'Endurance', the Imperial Trans-Antarctic Expedition, despite suffering from
malaria. Known by the nickname of Mick during the expedition, McIlroy was described by
Endurance author
Alfred Lansing as "a handsome, aristocratic-looking individual" who was seen by his fellow crew as a "man of the world". He was known to entertain his crew mates with the stories of his exploits sailing around the world. McIlroy was also in charge of a sled-dog team when the expedition was cast away on the
Weddell Sea. He also played the banjo in the team's musical ensemble. After the castaways found a refuge on
Elephant Island, McIlroy was the surgeon performing the amputation of
Perce Blackborow's
gangrenous toes, with Macklin serving as
anaesthetist, carefully administering a tiny quantity of salvaged
chloroform as
anaesthesia. After the rescue of McIlroy and his comrades, the physician was awarded the Silver
Polar Medal. ==Second Shackleton expedition==