John James Abert (1791-1863), at the time of the letters, was the Chief of the United States Topographical Engineers, a position he held from 1828 to 1861. Born in Maryland in 1791, Abert entered West Point on January 18, 1808. After graduating in 1811, he refused a commission, and instead practiced law. Abert served as a private soldier during the War of 1812. In 1814, the Army reappointed him as a major in the Topographical Engineers where he took command of a series of surveys along the Atlantic Coast. Ten years later, his rank was raised to Lieutenant Colonel, and in 1828, he was promoted to Colonel and Chief of the Topographical Engineers. Abert held the position until 1861, when he retired due to ill health. During the 1830s, Abert was also involved in the moving of the Native Americans to reservations under the Indian Removal Bill of 1830, and he acted as Commissioner and Agent to the Creek and Wyandotte Indians in 1833-34. Abert died January 27, 1863 in Washington, D.C. James William Abert (1820-1897), son of John James Abert, also served with the Topographical Engineers. Like his father, he attended West Point, and, after graduating in 1842, was assigned to the Fifth United States Infantry. In 1843 he was transferred to the Topographical Engineers. James Abert sketched for Fremont on the first part of his 1845 expedition, and, later, Fremont gave command of the Canadian River mission to Lts. Abert and Peck. While on the mission, Abert kept written accounts, drew maps, and made sketches and watercolors of the Native Americans, Bent's Fort, and the native flora and fauna. In 1846, Abert and Peck surveyed New Mexico and again kept journals of the regional characteristics and peoples. Abert also taught drawing at West Point, was a business man in Cincinnati, served as examiner of patents in Washington, D.C., and was a professor of English Literature at the University of Missouri. He died at his home in Newport, Kentucky, on August 10, 1897. George William Featherstonhaugh (1780-1866) was the first United States appointed geologist. Born in London in 1780, he emigrated to America in 1807 and settled in Duanesburg, New York. He moved to Philadelphia in 1831 where he published the Monthly American Journal of Geology and Natural History and made surveys along the Atlantic coast. In 1834, the U.S. government appointed him as the official U. S. geologist, and authorized him to make a geological report of Missouri and Arkansas, and later other regions. In 1838, Great Britain commissioned him to survey and define the boundary between Maine and Canada. In 1845 he was appointed consul for the British government at Havre, France, where he died in 1866. Thomas Fitzpatrick (1799-1854), mountain man trapper, fur trader, guide, and scout; acted as guide on the 1845 Fremont expedition, and accompanied Abert and Peck on the Canadian River Mission. Known as "Broken Hand" due to the loss of two fingers during a gun battle, Fitzpatrick was appointed an Indian Agent in 1845 due to his mountain man knowledge and experience. As such, he was instrumental in a number of peace treaties. He worked under John Abert as topographical engineer.