 Meant to be a central vessel in the fleet, the louchuan was equipped for boarding and attacking enemy vessels, as well as with siege weapons including traction trebuchets for ranged combat.Historical records relating to the louchuan are found in sources such as the Song dynasty military treatise "Wujing Zongyao", written during the Song dynasty, and the "Taibai Yinjing" from the Tang dynasty.From the latter (as translated by British biochemist, sinologist, and historian Joseph Needham), the tower ships were described as