An illustration of a multistage rocket from the Huolongjing, a Chinese military treatise written in the 14th century by Jiao Yu and Liu Ji, the preface added in the year 1412. This missile was called the "fire-dragon issuing from the water" (huo long chu shui), a two-stage rocket. When the carrier or booster rockets were about to burn out they automatically ignited a swarm of smaller rocket-arrows which issued through the dragon mouth and fell upon the intended enemy target. The design seems to have been for use mainly in naval warfare. Since the trajectory was very flat the weapon may be regarded as an ancestor of the modern exocet.