The One Hundred and Forty-sixth Infantry Illinois Volunteers was organized at Camp Butler, Ill., September 18, 1864, for one year, and Henry H. Dean appointed Colonel.

Companies C and B were ordered to Brighton, Ill., Companies D and H, Quincy, Ill., and Company F to Jacksonville, Ill., and were assigned to duty guarding drafted men and substitutes.  The remaining companies were assigned to similar duty at Camp Butler, Ill.

On 5th July, 1865, the Regiment was mustered out of service at Camp Butler, Ill.