Complex sentence: Between 1898 and 1901 he was a choral coach, and subsequently assistant conductor, at the Bayreuth Festspielhaus, and in 1902 he conducted the Paris premiere of "Götterdämmerung" by Wagner.
Split into simpler sentences: Between 1898 and 1901 he was a choral coach and subsequently an assistant conductor at the Bayreuth Festival. In 1902 he conducted the Paris premiere of "Götterdämmerung" by Wagner.