Adolf Hitler — apart from his graver sins — had lousy taste in the arts, applauding mediocrities like the sculptor Arno Breker and writer Gerhard Hauptmann, with the partial exception of music. Hitler adored Schubert, Mozart, Franz Lehár, and most famously, Wagner. Boycotting these great composers today because Hitler favored them would be like branding all vegetarians Nazis because Hitler professed to be a herbivore.

Richard Wagner, an indubitable Nazi favorite, had Bayreuth, an entire village in Germany, devoted to the performance and worship of his works, which became an impassioned family center, both nationalist and anti-Semitic. Hitler, who saw himself as a great conqueror, was presented with a town all too willing to be dominated by the so-called Thousand Year Reich.

Much has been written about Hitler, Wagner, and Bayreuth, usually by music critics with an insufficient grasp of history — or indeed of music. Wagner, as a figurehead of cultural politics, is best dealt with by a political historian like Brigitte Hamann, the Austrian author of “Hitler’s Vienna: A Dictator’s Apprenticeship” (2000) and the newly translated “Winifred Wagner: A Life at the Heart of Hitler’s Bayreuth” (Harcourt, 582 pages, $35).

Brilliantly translated by Alan Bance, a professor emeritus of German at the University of Southampton, “Winifred Wagner” offers a number of new insights, reminding us that art can be used to fuel hate and prejudice, as well as to express love. The book’s original title, “Winifred Wagner oder Hitler’s Bayreuth” (Winifred Wagner or Hitler’s Bayreuth) is probably more apt, if less sentimental, since the notion that Hitler’s Bayreuth had any heart at all is disproved within the book itself. The statuesque protagonist, British-born Winifred Wagner (1897–1980), married Wagner’s homosexual son Siegfried for the purpose of continuing the family dynasty, and produced four children against all odds.

Winifred — or “Winnie” as she was known, physically resembled a Valkyrie — the Norse goddesses who populate Wagner’s “Ring” opera cycle — and was a lifelong rabid fan of “Wolf,” as Hitler was nicknamed by the Bayreuth family circle. Even in the late 1970s, the American heroic tenor James King was not heroic enough to put up with Winnie, whom he described as a “frightening old lady” bombarding Bayreuth performers with memories of the good old Nazi days.

Some observers, including the director Hans-Jürgen Syberberg, who produced a 1975 documentary film starring a defiantly unrepentant Winnie, implied that unlike most former Nazis, at least she was not hypocritical. Yet Ms. Hamann suggests that instead of admiring Winnie for her supposed lack of hypocrisy, we should marvel at her abiding faith that there was nothing wrong with Hitler or Nazism; the real problem was with some of Hitler’s uncivil underlings. Winnie, as Ms. Hamann details, had no problem with eliminating Jews, but intervened to save — or lighten the persecution of — select Wagnerians who were only one-quarter Jewish. Rather than humanitarian, Winnie’s motives can be ascribed to her vainly delusional self-importance and self-image as an omnipotent Lady Bountiful.

Among the new incriminating information uncovered by Ms. Hamann — despite being impeded by the fact the official Wagner family archive is still closed to researchers — is the extent of the opportunistic Nazism of Winnie’s son, Wieland Wagner (1917–1966). Wieland has been widely praised for his directorship of the postwar Bayreuth Festival, and despite clearly lying about his Nazism to postwar authorities, Wieland never paid any price for his Hitler-worship.

There was no real artistic logic behind the racist choices made in Hitler’s Bayreuth. The great Wagner baritones Friedrich Schorr, a Hungarian Jew, and Herbert Janssen, a homosexual Aryan, were forced into exile. Yet the tenor Max Lorenz, who was famously gay despite a marriage of convenience with a Jewish woman, enjoyed Hitler’s personal protection. Perhaps then as now, Wagnerian tenors were rarer than heroic baritones?

The best cure after reading this compelling book about these vile dramatis personae is to listen to a newly republished radio broadcast of a Wieland Wagner-directed production of “Lohengrin” — one of Hitler’s early favorites — from the 1959 Bayreuth Festival on Orfeo (distributed in America by Qualiton.com). The cast under the stellar Croatian maestro Lovro von Mata includes the splendid German soprano Elisabeth Grümmer, Hungarian tenor Sándor Kónya, French baritone Ernest Blanc, and Belgian mezzo-soprano Rita Gorr. Together, they prove how music can be abstract and exalted enough to expunge any merely human baseness.

Mr. Ivry is author of biographies of Ravel, Poulenc, and Rimbaud, and the poetry collection “Paradise for the Portuguese Queen.”