In a medieval version of the nuclear arms race that would follow more than a millennium later, Charles Martel realized that the advantage provided by the stirrup was so “immense” that he had to do whatever it took to get it before his enemies did—even if that meant upending centuries of tradition and creating a brand-new form of government. In Lynn White Jr.’s study of the stirrup we find a classic example of a technology introduced for a simple reason (to make riding horses easier) leading to vast and complicated consequences never imagined by its inventors (the rise of medieval feudalism).
