Ed Zubrow on the War Requiem:

>I don't have a score, but I would be interested to know the harmony of the
>final amen.  I'm pretty certain it is not a standard cadence.

Until the final " - men" the tonality is around F sharp (the chord
consisting of F sharp and C natural begins the work and permeates it
throughout) but with bare fifths and augmented fourths, with the second or
ninth hovering around on top, and no third to be found anywhere (the chorus
is unaccompanied in the last seven measures of the work, except for a final
F-sharp--C-natural interjection, pianissimo tenuto, from the bells), so
modality remains ambiguous (the dynamic is ppp dim.  e rall.) right up to
the final syllable, when the F-sharps and C-sharps go down one semitone to
become naturals and an A natural finally appears in Tenor I and Soprano I,
thus ending the work on a fermata securely in the remote key of F major,
pppp.  Let us sleep now.  Requiescant in pace.  Amen.

Alan Moss