John Ledyard (lĕd´yərd), 1751–89, American adventurer, b. Groton, Conn. He studied at Dartmouth for year, but left college to ship as a sailor. In 1776 he joined Capt. James Cook's last expedition. Having seen the Pacific Northwest and traded for furs there, he was fired with a desire to establish a post in the region. Though Cook had not found the fabled Northwest Passage, Ledyard was convinced that a practicable route could be found. Failing to obtain support in America for his scheme for an exploratory expedition, he went to France. There he was encouraged by Thomas Jefferson and John Paul Jones, but failed to secure funding. He then undertook to walk across Europe and Siberia. Russia at first refused permission, but in 1787 he reached St. Petersburg and was permitted to start the long, dangerous journey that took him to Yakutsk. There, however, he was arrested and sent back. Ledyard was engaged in a plan (supported by Sir Joseph Banks) for exploring the African interior when he died in Cairo.
See biographies by H. Augur (1946), J. Zug (2005), and B. Gifford (2007).