Conrad Haas (1509–1576) was a military engineer of the Holy Roman Empire, who is often cited as the first person to describe a multistage rocket in writing, although some historians attribute that distinction to Jiao Yu in 14th Century China.
From an illustration and description in the 14th century Chinese Huolongjing of Jiao Yu is the oldest known multistage rocket; this was the 'fire-dragon issuing from the water' (火龙出水, huo long chu shui), used mostly by the Chinese navy.