This is all that is found at http://www.civilwardata.com

John B. Foster

Residence was not listed;
Enlisted as a Private
"A" Co. TN 1st Infantry

Sources used by Historical Data Systems, Inc.:
- Index to Compiled Military Service Records.

……..

This is found at Fold3

John B. Foster, Company A, 1st Regiment Tennessee Infantry, a Widow’s Class pension was filed August 15, 1866, Application No. 131,144, Certificate No. 169,419 [No death date listed]

T289: Organization Index to Pension Files of Veterans Who Served Between 1861 and 1900.

You might be able to access this record on Ancestry.com I no longer have a subscription