The song first appears in Peter Buchan's manuscripts, undated, but I would hazard a guess at c1825-45. It is highly typical of Peter's adaptations of earlier songs and is unquestionably based on the English broadside ballad of Pretty Peggy of Derby, therefore it is highly unlikely that it refers to anything real that might have happened in or near Fyvie. Irish Dragoons like many regiments took the rout i.e., moved around the country a lot in the 18th century, particularly during the Napoleonic War.