Why is it said that Roald Amundsen’s South Pole expedition was a secret mission?

               Amundsen planned to sail to the North Pole, and explore the Arctic Basin. But, later he decided to reroute to Antarctica. He kept this as a secret from everyone except his brother, who knew that Amundsen was heading to the South Pole, instead to the North.

               Roald Amundsen even made his crew believe they were embarking on an Arctic voyage, and revealed their destination only when the expedition was leaving their last port of call.

               He set up his Antarctic base in the Bay of Whales, on the Great Ice Barrier. The base was 96 kilometres closer to the Pole than the base of the English explorer Robert Scott, who was heading a British expedition at the same time. But Amundsen was more skilful and he used skis and sledge dogs which ensured rapidness. Robert Scott used Siberian ponies, instead of sledge dogs but they failed to brave the weather.