Desmond Shawe-Taylor wrote of her in the New Grove Dictionary of Opera: "No one within living memory surpassed her in sheer beauty and consistency of line and tone."
[2] She received her early musical training in Oslo and made her stage debut at the National Theatre, as Nuri in Eugen d'Albert's Tiefland in 1913.
Later that year she signed up with the newly created Opera Comique in Oslo, under the direction of Alexander Varnay and Benno Singer.
On 31 May 1930 she married her second husband, the Norwegian industrialist and lumber merchant Henry Johansen, who subsequently helped her in expanding her career.
Flagstad was first noticed by Otto Hermann Kahn, then chairman of the board of the Metropolitan Opera, on a trip to Scandinavia in 1929, and Met management made overtures soon after.
Upon leaving St Moritz, Bodanzky's parting words for Flagstad were "Come to New York as soon as you know these roles (Isolde, the three Brünnhildes, Leonore in Fidelio, and the Marschallin in Der Rosenkavalier).
Her debut at the Met, as Sieglinde in Die Walküre on the afternoon of 2 February 1935, created a sensation, though it was not planned as a special event.
[5] In 1936 and 1937, Flagstad performed the roles of Isolde, Brünnhilde, and Senta at the Royal Opera House, Covent Garden, under Sir Thomas Beecham, Fritz Reiner and Wilhelm Furtwängler, arousing as much enthusiasm there as she had in New York.
Flagstad did get her way, though; she went over Johnson's head and discussed the matter with the Met's board of directors, particularly David Sarnoff, RCA and NBC founder and chairman.
Having received repeated and cryptic cablegrams from her husband, who had returned to Norway a year and a half earlier, Flagstad was forced to consider leaving the United States in 1941.
Though dismissing the political implications of the departure of someone of her fame from the United States to German-occupied Norway, it was nonetheless a difficult decision for her.
Even more importantly, her 20-year-old daughter Else had married an American named Arthur Dusenberry and was living with her new husband on a dude ranch in Bozeman, Montana.
Nonetheless, against the best advice of her friends and colleagues, including former president Herbert Hoover, who pleaded with her to stay out of Europe, she returned to Norway via Lisbon, Madrid, Barcelona, Marseille, and Berlin in April, 1941.
[5] Though during the war she performed only in Sweden and Switzerland, countries not occupied by German forces, this fact did not temper the storm of public opinion that hurt her personally and professionally for the next several years.
In defense of Flagstad's husband, Henry Johansen, after his death it was revealed that during the occupation he was arrested by the Gestapo and held for eight days.
Despite the great fanfare surrounding her return to the Met in early 1951, and her success in resuming her roles there, Flagstad decided that it would be her final year singing Wagner on the stage.
She had also developed an arthritic hip in mid-1951 (and had to consult doctors in New York); this further made the operatic stage difficult for her, especially when singing Wagner.
To celebrate the Coronation of Queen Elizabeth II, in July 1953 Madam Flagstad appeared as Dido in Bernard Miles reconstructed 'Globe Theatre' which was erected inside the Royal Exchange building in the City of London.
(The songs are better suited to the lyric soprano voice he idealised throughout his life, as exemplified by Elisabeth Schumann and ultimately his wife Pauline de Ahna.
He sent Flagstad a letter, accompanied by a collection of his own works which he desired her to consider adding to her repertoire, and requested that she give the premiere – together with "a first-class conductor and ensemble" – of these four new orchestral lieder, at that point still in the publication process.
"Frühling" indeed, gave such trouble that Legge, in promoting the concert, was two days before the event advertising the Strauss as "three songs with orchestra".
In the event, Flagstad rose to the occasion and included "Frühling" (excluding, however, the highest note), and the close of "Im Abendrot" was followed by a respectful silence in memory of Strauss.
The concert, which aside from the Strauss songs consisted of Wagner (including Isolde's Liebestod and Brünnhilde's Immolation), received favorable reviews; recordings of Flagstad's contributions were made from the radio broadcast, and are today commercially available.
Flagstad added "September", "Beim Schlafengehen", and "Im Abendrot" to her repertoire, and recordings (technologically superior to those taken at the premiere) exist of these performed in concert; she did not, however, sing "Frühling" again.
She even made some stereophonic recordings, including excerpts from Wagner's operas with Hans Knappertsbusch and Sir Georg Solti conducting the Vienna Philharmonic Orchestra.
In 1958, she sang the part of Fricka in Wagner's Das Rheingold, the first instalment in Solti's complete stereophonic set of the Ring Cycle, released by Decca on LP and reel-to-reel tape.
Because she was aged 57, she was unsure of her capacity to reach the top Cs in Act II, and agreed to Elisabeth Schwarzkopf providing her voice for this purpose.
Two live concerts are of particular historical significance: In 1956, she moved to Decca where in the autumn of her career further important studio recordings followed: Almost to the end of her life, Flagstad continued to sing in fine voice, although she increasingly sang mezzo-soprano material or in a mezzo range: besides the Rheingold Fricka (a mezzo role), Decca planned to cast her also as the Walkure Fricka and the Gotterdammerung Waltraute for its complete Ring (in the event, both roles were sung by Christa Ludwig), and also to record her in Brahms’ Four Serious Songs and Alto Rhapsody; that these plans were shelved only by her final illness and death stands as a testament to her superbly consistent vocal abilities, and to the respect and affection in which she was held to the end by record companies and the public.