武经总要
The "Wujing Zongyao" describes a flamethrower with a double-acting two-piston cylinder-pump capable of shooting a continuous blast of flame. The first Chinese battle to use the double-piston pump flamethrower was the Battle of Langshan Jiang in 919 AD. In the Battle of Langshan Jiang (Wolf Mountain River, 狼山江), the naval fleet of the Wenmu King of Wuyue defeated the fleet of the Kingdom of Wu because he had used 'fire oil' (huo yóu, 火油) to burn his fleet; this signified the first Chinese use of gunpowder in warfare, since a slow-burning match fuse was required to ignite the flames. Greek fire is likely based on distilled petroleum and is a weapon of Byzantine origin. The Chinese author Lin Yu explained in his book of 919 AD that Greek fire was acquired from their Arab maritime trade contacts in the Indian Ocean. Furthermore, the Chinese had been using the piston syringe since the Han Dynasty (202 BC – 220 AD). However, it was the later "Wujing Zongyao" that would provide the first illustrated drawing and greater textual explanation for how this flamethrower operated. In describing the drawn illustration of the flamethrower in the book, the "Wujing Zongyao" states: