civil war records - 2nd Great Grandfather

HI - I am trying to track information on my 2nd Great Grandfather, James McIntosh.

He was born in Mass, but what I understand that he joined the Union forces once he moved to Wisconsin.   I found an index card with his name and looks like invalid index card that mentioned his wife, Cornelia.   I did try to go to Fold3 and did not have much luck in finding records.   The only thing that I could find is that he might have been injured during Bull Run.

Any suggestion would be great.    He lived in Lodi Wisconsin during this time.