 During the reign of the Yongle Emperor (1402–1424), the Shenjiying, a specialized military body, was in part a cavalry force that utilized tubes filled with inflammable materials holstered to their sides, and also a firearm infantry division that handled light artillery and their transportation, including the handling of gun carriages.The first recorded use of land mines occurred in 1277 when officer Lou Qianxia of the late Song Dynasty, who is credited with their invention, used them to kill Mongol soldiers.Jiao Yu wrote that land mines were spherical, made of cast iron, and their fuses were ignited by the enemy movement disturbing a trigger mechanism.