Conrad Haas (1509–1576) was a military engineer of the Holy Roman Empire, who is believed to be the first person to describe a multistage rocket in writing.
Haas was perhaps born in Dornbach (now part of Vienna). As the Zeugwart (equipment manager) and arsenal master of the Imperial Austrian army under Ferdinand I, he went to Hermannstadt, Siebenbürgen (Transylvania) (now Sibiu/Hermannstadt, Romania) in 1551, where he oversaw operation of the arsenal.
Between 1529 and 1556, he wrote a book in German language in which he described rocket technology, involving the combination of fireworks and weapons technologies. This manuscript was discovered in 1961, in the Sibiu public records (Sibiu public records Varia II 374).
"But my advice is for more peace and no war, leaving the rifles calmly in storage, so the bullet is not fired, the gunpowder is not burned or wet, so the prince keeps his money, the arsenal master his life; that is the advice Conrad Haas gives."