What is the unit designation at the vary top of the discharge certificate you describe? And where is his place of residence & birthplace which are usually stated in these documents?
And yes, it appears that he served the one full year he committed to and was discharged at the end of the period due to being underage and not subject to conscription, this would be considered honorable.
The Index to Tennessee Confederate Pension Applications lists a: J. W. Darwin, #S 16134, 25th Infantry, from Trousdale County. You can obtain these papers through the service noted in the Red enclosed box above.
George Martin
John W. Darwin, Private, 4th Battalion*, Tennessee Cavalry, subscribed and swore allegiance to the United States at Nashville, Tennessee on February 10, 1864**, resident of Jackson County, Tennessee, Dark Complexion, Dark Hair, Hazel Eyes, 5' 6", this is the one and only card in his file.
* His cards are filed with those of the 4th Tennessee Cavalry Regiment which could either be Branner's or Murray's. However, Companies E, later K of Murray's 4th Cavalry Regiment was raised with men from Jackson County. Company G of the 25th Tennessee Infantry was also raised with men from Jackson County. [Tennesseans in the Civil War]
** This would deny him a Confederate pension from the state of Tennessee
1860 United States Federal Census about John Darwin
Name: John Darwin
Age in 1860: 15
Birth Year: abt 1845
Birthplace: Tennessee
Home in 1860: District 11, Jackson, Tennessee
Gender: Male
Post Office: Flyns Lick
Household Members:
Name Age
George C Darwin 46
Margret Darwin 37
Adline Darwin 18
John Darwin 15
Louisa Darwin 13
Margrey Darwin 11
Richard Darwin 8
Uphand Darwin 6
Julia Darwin 4
Lusita Darwin 2
John Prier 18