Keilberth conducted at the Bayreuth Festival from 1952 until 1956,[1] with complete WagnerRing Cycles from 1952, 1953 and 1955, as well as a well-regarded recording of Die Walküre from 1954 (the whereabouts of rest of the cycle are unclear) in which Martha Mödl, perhaps the greatest Wagnerian actress and tragedian of her time, sang her only recorded Sieglinde. He made the first stereo recording of the Ring Cycle in 1955, as well as a so-called "second cycle" with Mödl, rather than Astrid Varnay, as Brünnhilde. Mödl's accounts of Brünnhilde, from the 1953 Ring as well as the 1955 "second cycle," are her only recordings of the role other than Wilhelm Furtwängler's 1953 Rome Ring and commercial Walküre in 1954.
He died in Munich in 1968 after collapsing while conducting Wagner's opera Tristan und Isolde in exactly the same place as Felix Mottl was similarly fatally stricken in 1911.[1] His final recording, a Meistersinger, came a month before his death—at the Bavarian State Opera on 21 June.