McClure, Sir Robert John Le Mesurier (1807-1873), a British Arctic explorer. McClure was born in Ireland. He joined the Royal Navy in 1824 and took part in two Arctic explorations, 1836-37 and 1848-49. During 1850-54 he crossed the Northwest Passage between the Pacific and Atlantic oceans, but not entirely by ship. As commander of the Investigator, he sailed eastward from the Pacific until his ship became frozen in the ice off the northern coast of Banks Island. McClure and his men continued eastward on foot until a rescue party picked them up. They then sailed back to England. McClure was knighted on his return.