This drawing seems to titled and dated wrong on the Library of Congress page for this image. The rainy evening retreat of Pope’s forces was on August 30, not the 28th, and it was to Centreton, not Groveton or Mnassas Junction. Where the title and date came from is not identified on LOC page.
Title: “Retreat of the Army of the Rappahannock (Gen. Pope) to Groveton, Manassas Junction”; drawing by Edwin Forbes, date August 28, 1832 on the LOC page for this image.
Library of Congress image.