After his return to the National Theatre in 1941, Haken quickly became one of the most popular artists in the city. In his early years he developed a strong artistic partnership with conductor Vaclav Talich who greatly admired the young the bass. He was a much loved Kecal in The Bartered Bride. Among his chief roles at the theatre were Basilio in The Barber of Seville, Beneš in Dalibor, Daland in The Flying Dutchman, Mephistopheles in Faust, Mumlal in The Two Widows, Paloucký in The Kiss, Prince Gremin in Eugene Onegin, Ramfis in Aida, Rocco in Fidelio, Van Bett in Zar und Zimmermann, Vodník in Rusalka, Volfram Olbramovič in The Brandenburgers in Bohemia, Zechariah in Nabucco, and the title role in A Life for the Tsar. One of his last appearances at the house was in 1992 in a production of František Škroup's Columbus.
