Source: http://www.army.mil/cmh/Default.htm

Note: This is not my ancestry. I have NO additional information. I am just passing along information that may be useful.

JOSSELYN, SIMEON T.
Rank and organization: First Lieutenant, Company C, 13th Illinois Infantry. Place and date: At Missionary Ridge, Tenn., 25 November 1863. Entered service at: Amboy, Ill. Born: 14 January 1842, Buffalo, N.Y. Date of issue: 4 April 1898. Citation: While commanding his company, deployed as skirmishers, came upon a large body of the enemy, taking a number of them prisoner. Lt. Josselyn himself shot their color bearer, seized the colors and brought them back to his regiment.