Scurvy took a terrible toll in the Age of Sail, killing more sailors than were lost in all sea battles combined. The threat of the disease kept ships close to home and doomed those vessels that ventured too far from port. The willful ignorance of the royal medical elite, who endorsed ludicrous medical theories based on speculative research while ignoring the life-saving properties of citrus fruit, cost tens of thousands of lives and altered the course of many battles at sea. The cure for scurvy ranks among the greatest of human accomplishments, yet its impact on history has, until now,...