Simplify the following text for a Grade 7 native English-speaking person.
Original: The author Hertha Pauli , who was born in Austria had to flee from the persecutions during the Second World War . In 1943 , she found that many Americans thought that `` Silent Night '' was an American popular tune .
Simplified: In 1943 , the Austrian exile Hertha Pauli wrote the book `` Silent Night .