Business
The deadliest threat is often a slow illness, not the spectacular hazards people fear. At sea, scurvy killed more men than storms, shipwrecks, combat and all other diseases combined, over two million in all. One disaster, in which a crew of about two thousand came home as about two hundred, finally set off serious research.
A disease tied in people's minds to one setting can really come from a diet that lacks something. Scurvy was seen as a sailors' illness, yet it struck in northern winters, sieges, prisons and failed harvests. It appeared wherever people lived on food short of vitamin C.
A controlled test can show the answer and still change nothing if well-placed experts contradict it. Decision-makers follow the people who have their ear, not the strongest data. The same answer won out only when a well-connected insider pushed it through official channels.
Knowing that a remedy reverses a disease is not the same as seeing that a daily dose stops it from starting. Mariners learned that lemon juice healed the sick, but those in charge did not grasp it as prevention. Getting from one insight to the other took about sixty years of work by several people.
A cure that practical people had already found can be lost again once experts adopt a theory that cannot explain it. Sailors' plain observation that fresh food and citrus helped was pushed aside by learned talk of foul vapours and unbalanced body fluids. Sailors kept dying for generations from a disease that had once been treatable.
Useful remedies may be on the table, but an authority that cannot say why they work will often not act on them. They lose out to cheaper, more convenient ideas that fit the accepted theory. Without understanding, there is nothing to tell a real cure from a fashionable one.
When a proven remedy is costly or hard to supply, institutions drift toward substitutes that are easy and cheap, even if they do not work. Sea water and similar odd cures were favoured over citrus mainly because they were practical. The result was a long, deadly delay.
A disease can be practically beaten long before anyone knows its true cause. Scurvy was all but eliminated at sea by the end of the eighteenth century, while its link to a missing nutrient was still unknown. The everyday regimen ran far ahead of the science.
When losses seem unavoidable, organisations stop trying to prevent them and budget for them instead. Ships carried up to half again as many men as they needed, and owners counted on huge death tolls on long voyages. Planning around the deaths removed the pressure to solve the problem.
Whoever keeps their people healthy can stay out longer and fight harder, and that can settle wars. A navy weakened by disease could not hold its ground, while one with a daily citrus ration could stay at sea long enough to blockade an enemy and win. The cure set how far ships could go and which battles were won.