Image from The Story of Mathematics
In 1535, a young Venetian called Nicolo Fontana won the Mathematics Competition at Bologna University. His achievement, formerly considered impossible, involved using the square roots of negative numbers. Ten years later, this work was claimed and published by Cardano, along with work by Cardano's student, Ferrari, whose formula was inspired by Fontana's work.
A bookkeeper as well as an engineer in the Venetian army, Fontana was a topographical surveyor who designed fortifications. He was wounded in an attack by the French army, and the resulting facial scar stuttering gave rise to the epithet he became known by, Tartaglia, the Stammerer.