A little more on pension files:
Soldier's pension: The vet has survived [1832 for Rev War] long enough to qualify for a pension. His service record will be included along with testimony from others who knew of his service. You may, or may not, find additional genealogical info. The veteran's date and place of birth should be included and his date and place of death [terminating the pension]. You may find marriages, spouses, and children mentioned, but don't count on it.
Invalid pension: Soldier was injured, wounded or sick and received a pension. His medical files and service record should be included. Documents filed by fellow soldiers, physicians, family members testifying as to his infirmity. Identify all of those people as to relationship to the vet!
Widow's pension: The surviving spouse of the veteran qualified for a pension. She had to provide proof of marriage, so look for marriage license or some similar document. Also, names of children, with birth info should be included. Documentation about the soldier [service record, affidavits, death record, etc.] should be included as well.
In any pension file, write down the name of every person mentioned in the documentation and find out how that person was related to the soldier or soldier's widow. Wes he/she a sibling, child, parent, cousin, step-relative, fellow soldier, family physician, spouse, in-law? You might be able to track down your person in the records of one of those folks!