Complex sentence: The Persians unsuccessfully attacked Palmyra in 265 but were repelled, and Odaenathus defeated Shapur again in 266 near Ctesiphon, then headed north to repel the Goth attacks on Asia Minor in 267, but was assassinated along with his son Hairan on his returning way.
Split into simpler sentences: The Persians unsuccessfully attacked Palmyra in 265 but were repelled, and then defeated by Odaenathus in 266 near Ctesiphon. The Palmyrene monarch then headed north to repel the Goth attacks on Asia Minor in 267, but was assassinated along with his son Hairan on his returning way.