Virgil Thomson on the 1952 protests against Don Carlo at the Met:
Just for pleasure, and also to impress a visitor from Europe, your announcer dropped in last Monday night at the Metropolitan Opera for a performance of Verdi’s Don Carlo ... It was something of a surprise to learn that the performance was being picketed. Investigation revealed the following facts. The Archdiocesan Union of the Holy Name Society of New York, the American Society for the Preservation of Sacred, Patriotic, and Operatic Music, and the Children’s Drama Guild have all made protests to the Metropolitan management. The latter group had already asked the Manhattan Supreme Court, back in 1950, for a declaratory judgment enjoining the Metropolitan Opera Association from disseminating subversive anti-religious propaganda. This suit is still awaiting action....
The signs carried by the picketers, who are about thirty in number, bore the following legends:
“The opera Don Carlo is a mockery of religion.”
“The opera Don Carlo is anti-state and anti-religious.”
“Stop Sovietizing operas.”
“Moscow termites invade the ‘Met.’”
“Don’t support ‘Met’ Opera as long as they hire subversives.”
“Who gets the money that the ‘Met’ loses?”
“Planned deficit financing is anti-American.”
I quote from the excellent new Library of America edition of Thomson's writings, edited by Tim Page. Thomson further notes that the protesters had earlier been confused about their dates, showing up on a night when Die Fledermaus was playing.
Needless to say, all of this anticipates the Klinghoffer demonstrations that unfolded this fall — not least the scene on opening night, when some protesters upbraided operagoers for attending an anti-Semitic, pro-terrorist work, not realizing that the opera on offer was The Marriage of Figaro.