 Between 1842 and 1845 while Griswold was collecting material for Prose Writers of America he discovered the identity of Horace Binney Wallace , who had been writing in various literary magazines at the time ( including Burton 's ) under the pen name William Landor . Wallace declined to be included in the anthology but the two became friends , exchanging many letters over the years . Wallace eventually ghostwrote Griswold 's Napoleon and the Marshals of the Empire ( 1847 ) . 
