The Master of Crossbowmen (French: Maître des Arbalétriers) or more precisely, Master of Arbalesters or Master of Archers was the title of a commander of the Infantry of the French army (the "host") in the Middle Ages and the Renaissance.
The position was an honorific title, not a military rank, created by Louis IX.
The position existed until the reign of François I, when its duties were transferred to the Grand Master of Artillery.
The Master of the Crossbowmen commanded all archers (longbow, arbalest, crossbow, etc.
), engineers and workers on siege engines, sappers ("sapeurs") and miners for mining fortifications during siege warfare.