John George Nicolay (born February 26, 1832, as Johann Georg in Essingen, Rhenish Bavaria – September 26, 1901) was an American (German-born) biographer and secretary of Abraham Lincoln. After the death of the President, Nicolay became United States Consul at Paris, France (1865-69). For some time after his return to the United States, he edited the Chicago Republican.
He was marshal of the United States Supreme Court (1872-87). In 1881, Nicolay wrote The Outbreak of the Rebellion.Nicolay and John Hay, who had worked alongside Nicolay as assistant secretary to Lincoln, collaborated on the official biography of the 16th President.John G. Nicolay in Wikipedia