Complex sentence: He made his first public appearance in London, with the London Philharmonic Society, in 1897 singing "Wotan's Farewell" which he later sang at his first public appearance in Chicago on the same year with Theodore Thomas Orchestra.
Split into simpler sentences: He made his first public appearance in London with the London Philharmonic Society in 1897. He sang "Wotan's Farewell", which he later sang at his first public appearance in Chicago in the same year with the Theodore Thomas Orchestra.