Christopher Columbus

Viking reached newfoundland, canada, and greenland long before Columbus ever arrived. The first thing he ever did when he arrived was kill loads of "indians" for nothing more than sheer fancy. He was a brute, and the only reason Sapin sponsored him was that they were weak as hell and took a shot in the dark.

Interesting story as well, without the prosperity the Americas brought Europe the Assanid empire (the muslims) who had already conquered Byzantium and most of Spain, were poised to conquer Italy and take over Europe. This would have make Islam the dominant european religion, meaning all of america would have been Islam. Crazy to think about.