Asa Collier--residence and birthplace Pope Co., IL. Age 20, 5'8". Dark hair and eyes, single, farmer. Joined 56th Co K, 11-7-61 at Golconda by Wm. R. Floyd for 3 yr. Mustered in at Shawneetown, IL 2-27-62. Discharged for disability 3-10-62.
Francis Collier--residence & birthplace Pope Co., IL. Age 37, 6', dark hair, blue eyes, married, farmer. Joined 29th Co H, Aug. 12, 1862 at Hardin Co., IL by J.S. Herod for 3 yr. Mustered in Nov. 13, 1862. Deserted Nov. 1, 1863. Transferred from 131st Oct 30, 1863.
Thomas Collier--residence & birthplace Pope Co. Age 37, 6', dark hair, blue eyes, married, farmer. Pvt Co B, 131st--joined 8-12-62 in Hardin Co., IL by J.S. Herod for 3 yr. Mustered in 11-13-62. Transferred to Co D at consolidation. Transferred to Co H 29th IL Inf.
Thomas Collier, Jr.--residence & birthplace Pope Co., IL. Age 18, 5'5 1/2", Light hair, blue eyes, single, farmer. Joined Pvt. Co K 56th 11-7-61 at Golconda by Wm. R. Floyd for 3 yr. Mustered in 2-27-62 at Shawneetown. Discharged with disabilities 3-7-63.
Asa was ill, so he likely was discharged from Paducah, KY if in fact he ever left home. Measles were in southern IL in the latter part of 1861, and smallpox in Paducah in the early part of 1862.
Why the 56th IL Inf was nicknamed Mechanic's Fuseleers--I have no idea except in the earliest part of enlisting, almost all of the regiments in southern IL had nicknames. It was made up of men from all walks of life--farmers, businessmen, bankers, etc. And they had regular guns!!
Company B of the 56th, and many others from different companies, were killed in the General Lyon explosion off Cape Hatteras, shortly before the end of the war. Most had served for over 3 yrs. and were on their way back home.
If Francis and Thomas Sr. are not the same person, then you'd have to check Francis' military records to see if he actually deserted, or was discharged from the 131st. Some are listed as deserters, but ended up serving in other regiments (other than the ones originally assigned to them); some transferred to the navy, some were killed but it was never reported to the officer in charge. His actual file should tell you what happened.
Hope this helps.