sentences:  Emperor Leo VI the Wise replaced Argyros with the more energetic Himerios, but Leo of Tripoli forestalled the Byzantines, turning back west and heading for the Empire's second city, Thessalonica, which he sacked after a three-day siege on 31 July 904.The sack of the city brought the Muslim fleet enormous booty and many captives who were taken to be sold as slaves, including the eyewitness John Kaminiates, who wrote the main account of the city's siege and fall.Arab sources, confusing Thessalonica with Attaleia, erroneously report that Leo sacked the latter city.