Complex sentence: His favourite harem girl was Emetullah Rabia Gülnûş Sultan, who was a slave girl and later his wife, was taken prisoner at Rethymnon (Turkish Resmo) in the island of Crete.
Split into simpler sentences: His favourite harem girl was Emetullah Rabia Gülnûş Sultan, a slave girl and later his wife. She was taken prisoner at Rethymnon (Turkish Resmo) on the island of Crete.