Ralph Vaughan Williams used the tune in his score for the film "49th Parallel", most obviously when the German U-boat surfaces in Hudson Bay shortly after the beginning of the film. Flor Peeters wrote an organ chorale setting "Ein feste Burg" as part of his Ten Chorale Preludes, Op. 69, published in 1949. More recently it has been used by band composers to great effect in pieces such as "Psalm 46" by John Zdechlik and "The Holy War" by Ray Steadman-Allen. The hymn also features in "Luther", an opera by Kari Tikka that premiered in 2000. It has also been used by African-American composer Julius Eastman in his 1979 work "Gay Guerrilla", composed for an undefined number of instruments and familiar in its recorded version for 4 pianos. Eastman's use of the hymn can arguably be seen as simultaneously a claim for inclusion in the tradition of "classical" composition, as well as a subversion of that very same tradition.