Colonel Perrin's book is a bit confusing. He wrote of Four flags his South Carolina Brigade captured in the last charge against the 1st Corps. I don't know how the "Large Flag of the 149th PA" would have been on the opposite side of the field. I think he meant another Pennsylvania regiment. It is confusing, not many of the Union regimental histories were much help at the Library of Congress.
Thank you and have a good evening,
Shawn Prouty