Q: Stravinsky's Rite of Spring caused a ruckus in Paris, but which piece actually got him arrested in Boston?
A: In 1940 the Boston police arrived at Symphony Hall, confiscated the instrument parts to Stravinsky's orchestration of "The Star Spangled Banner", and arrested him for "tampering with public property". He was charged with changing the traditional harmonies.
Sources: This story can be found with the Koch release, Histoire de Soldat, Premieres & Rarities. It's also discussed in the book The Apollonian Clockwork by Louis Andriessen and Elmer Schönberger. According to this, Stravinsky was arrested for the unconventional major seventh chord in his arrangement of this piece.
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