 At age 17 , Booth made his stage debut on August 14 , 1855 , in the supporting role of the Earl of Richmond in Richard III at Baltimore 's Charles Street Theatre . The audience hissed at the inexperienced actor when he missed some of his lines . He also began acting at Baltimore 's Holliday Street Theater , owned by John T. Ford , where the Booths had performed frequently . In 1857 , Booth joined the stock company of the Arch Street Theatre in Philadelphia , Pennsylvania , where he played for a full season . At his request he was billed as " J.B. Wilkes " , a pseudonym meant to avoid comparison with other members of his famous thespian family . Author Jim Bishop wrote that Booth " developed into an outrageous scene stealer , but he played his parts with such heightened enthusiasm that the audiences idolized him . " In February 1858 , he played in Lucrezia Borgia at the Arch Street Theatre . On opening night , he experienced stage fright and stumbled over his line . Instead of introducing himself by saying , " Madame , I am Petruchio Pandolfo " , he stammered , " Madame , I am Pondolfio Pet — Pedolfio Pat — Pantuchio Ped — dammit ! Who am I ? " , causing the audience to roar with laughter . 
