On April 6, 1909, American explorer Robert Peary accomplishes a long elusive dream, when he, assistant Matthew Henson and four Inuits reach what they determine to be the North Pole. Decades after Peary’s death, however, navigational errors in his travel log surfaced, placing the expedition in all probability a few miles short of its goal.

Peary, a U.S. Navy civil engineer, made his first trip to the interior of Greenland in 1886. In 1891, Henson, a young African American sailor, joined him on his second arctic expedition. Their team made an extended dogsled journey to the northeast of Greenland and explored what became known as “Peary Land.” In 1893, the explorers began working toward the North Pole, and in 1906, during their second attempt, they nearly reached latitude 88 degrees north–only 150 miles from their objective.

In 1908, the pair traveled to Ellesmere Island by ship and in 1909 raced across hundreds of miles of ice to reach what they calculated as latitude 90 degrees north on April 6, 1909. Although their achievement was widely acclaimed, Dr. Frederick A. Cook challenged their distinction of being the first to reach the North Pole. A former associate of Peary, Cook claimed he had already reached the pole by dogsled the previous year. A major controversy followed, and in 1911 the U.S. Congress formally recognized Peary’s claim.

In recent years, further studies of the conflicting claims suggest that neither expedition reached the exact North Pole, but that Peary and Henson came far closer, falling perhaps 30 miles short. On May 3, 1952, U.S. Lieutenant Colonel Joseph O. Fletcher of Oklahoma stepped out of a plane and walked to the precise location of the North Pole.