He was trained in singing by his father and made his debut at the age of twenty in the small role of The Hermit in Der Freischütz at the city theatre of Ulm.

His other Wagnerian roles at the Met were Telramund in Lohengrin, The Dutchman in Der Fliegende Holländer, Wolfram in Tannhäuser, Hans Sachs in Die Meistersinger von Nürnberg, and Kurwenal in Tristan und Isolde.

He also appeared with the company as Herr Fluth in Die Lustige Weibern von Windsor, Pizarro in Fidelio, and in the title role of Don Giovanni.

He returned to the festival in 1901 at the height of his career and appeared there regularly until 1906 in a variety of leading roles including Wotan, The Dutchman, Wolfram, and Amfortas.

[1] According to his entry in the Großes Sängerlexikon, Bertram possessed a voice "with an inexhaustible fullness of tone and expressive power" which made him an "incomparable" Wotan.

His successful roles outside the Wagner and Mozart repertoire included Mephistopheles in Faust, Lothario in Mignon, Dapertutto in The Tales of Hoffmann, and Tonio in Pagliacci.