Soon after resuming his naval duties, Scott revealed to the Royal Geographical Society his intention to return to Antarctica, but the information was not at that stage made public. Scott was forestalled by Shackleton, who early in 1907 announced his plans to lead an expedition with the twin objectives of reaching the geographic and magnetic South Poles. Under duress, Shackleton agreed not to work from McMurdo Sound, which Scott was claiming as his own sphere of work. In the event, unable to find a safe landing elsewhere, Shackleton was forced to break this promise. His expedition was highly successful, its southern march ending at 88°23′, less than 100 geographical miles from the South Pole, while its northern party reached the location of the South Magnetic Pole. However, Shackleton's breach of his undertaking caused a significant break in relations between the two men, with Scott dismissing his former companion as a liar and a rogue.