Question: William McKendree Gwin (October 9, 1805 – September 3, 1885) was an American medical doctor and politician, serving in elected office in Mississippi and California, in California he shared the distinction, along with which American explorer, politician, and soldier who, in 1856, became the first candidate of the anti-slavery Republican Party for the office of President of the United States?
Sentence (from "John C. Frémont"): During the 1840s, when he led four expeditions into the American West, that era's penny press and admiring historians accorded Frémont the sobriquet "The Pathfinder".
Relevant evidence: No