John Charles Frémont (January 21, 1813 – July 13, 1890), was an American military officer, explorer, the first candidate of the Republican Party for the office of President of the United States, and the first presidential candidate of a major party to run on a platform in opposition to slavery, although he lost to Democratic candidate, James Buchanan. In 1864, Frémont was the favored candidate of the Radical Republicans. Only a political deal with Lincoln kept Frémont from running. After the war, Frémont left politics, except for a brief stint as the territorial governor of Arizona.