The opera “Parsifal” by Richard Wagner premiered in Bayreuth, Germany.
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President Donald Trump banned transgender persons from joining the US military.
Albert Einstein's theory of gravitational redshift was proven after a telescope in Chile observed a black hole.
Italian adventurer and author Giacomo Casanova was arrested in Venice for his offensive remarks on religion.
The Summer Olympic Games opening ceremony was held outdoors for the first time ever.
President Harry Truman signed the National Security Act.
