Oceanic voyages during the Age of Sail were fraught with danger. Charts were often inaccurate, navigational aids were crude, and dangerous weather could appear at any time. At least as bad, sailors had to deal with the mysterious disease scurvy, which appeared a few months into a voyage before steadily tightening its grip. At first it was mild, with sufferers reporting malaise and sore joints. As time went on, the symptoms became steadily worse. Skin bruised easily, gums bled, teeth and hair fell out, and old wounds reopened. Left untreated, its victims declined steadily into lethargy and death.
It has been estimated the disease killed more than 2 million sailors between the 16th and 18th centuries. On a lengthy voyage, the loss of half the crew was common, although in extreme cases it could be much worse. Vasco da Gama lost 116 of 170 men on his first voyage to India in 1499, almost all to scurvy. In 1744, Commodore George Anson returned from a four-year circumnavigation with only 188 of the 1,854 men he had departed with, most losses because of scurvy. Midshipman (and future admiral) Augustus Keppel was one of the lucky survivors—at the cost of all his hair and teeth.
Despite many efforts to find a cure for scurvy, 18th-century science was ill-equipped for the challenge. Medicine was dominated by Hippocrates’ 2,000-year-old theories of balancing the four humors. Today is it known that a lack of dietary vitamin C (ascorbic acid) causes scurvy, but vitamins were not discovered until the 20th century. To compound matters, many nonhuman mammals can synthesize ascorbic acid. Cats and dogs on ships therefore remained perfectly healthy eating no fruit or vegetables, which seemed to point away from diet as scurvy’s cause.
But one young Scotsman rose to the challenge. James Lind, a Royal Navy surgeon, read the accounts of Anson’s voyage with horror and set out to find a cure. He started by surveying the existing literature and noted several clues that pointed toward diet. Seamen had long known that eating green vegetation could ward off scurvy. When Anson’s men started to exhibit the first symptoms of the disease during his passage around Cape Horn, he made his way to the fertile island of Juan Fernández, where his men gorged on a plant called “scurvy grass.” Early explorers in North America noticed that Native Americans, confined to a diet of dried meat during the winter, supplemented it with a tea made from pine needles. Lind also rediscovered the observations of John Woodall, surgeon general of the East India Company a century earlier, who noted that citrus fruit—especially lemons—had a dramatic effect on patients.
Lind was not alone in searching for a cure. Supposed remedies were offered by individuals ranging from respected men of science to dangerous crackpots. Perhaps most bizarre was the idea that drinking seawater would cure the disease. The Navy Board—always with an eye on controlling costs—eagerly endorsed this last proposal. Clearly, objective research was required, and Lind took a truly groundbreaking approach to the problem.
Lind carried out what has since been recognized as the first randomized clinical trial, on board the Royal Navy ship Salisbury in 1747. After two months at sea, scurvy began to appear among the crew. When Lind had 12 cases to treat, he divided them into pairs. All the men received the same care, food, and drink, plus one of six possible treatments. The first pair was given cider; the next, elixir vitriol (dilute sulfuric acid); another was given vinegar; the fourth, seawater; the fifth, a paste of plant extracts; and the final, two oranges and a lemon each day. The result of the trial was conclusive: Only the pair given citrus fruit made a rapid, immediate recovery.
Unfortunately, Lind was not the best person to promote his breakthrough. Still wedded to the established humor-based view of health, he tried to shoehorn his findings into it. The confusing result—A Treatise on the Scurvy—was published in 1753, in which only a few paragraphs were devoted to his shipboard experiment, and poor diet was identified as just one of several causes.
Lind also struggled to turn his discovery into a practical remedy. He knew ships lacked practical means of preserving lemons for extended periods at sea. He proposed manufacturing a concentrate made from lemon juice called a rob, but the boiling and distillation process destroyed almost all the vitamin C. As a result, when Captain James Cook was asked to try a number of possible remedies on his first voyage, he reported no measurable benefit from the rob.
In hindsight, Cook’s epic voyages were a poor test bed for possible cures when compared with other warships. A devoted and paternalistic leader with only small crews to manage, Cook dedicated enormous effort to the welfare of his men. He insisted on scrupulous cleanliness for men and ships, and he supplied fresh fruit and vegetables for them whenever possible. As a result, he lost almost no one to scurvy, irrespective of the proposed preventatives tested. With little conclusive evidence either way, the Royal Navy’s civilian administrators naturally chose to adopt inexpensive and readily available ones over costly fruit.
Nevertheless, the knowledge that citrus fruits cured scurvy began to spread steadily through the navy, a process that accelerated after Lind was appointed to the influential position of senior physician at Haslar Naval Hospital. Soon, a clear division of opinion began to form. On the one hand were the sailors and naval surgeons convinced by the evidence of their own eyes. On the other were shore-based administrators and classically trained physicians who dismissed such evidence as mere anecdote that failed to conform with any known theory of disease. It would take the crucible of war and another Scottish naval surgeon to resolve the issue.
Gilbert Blane was appointed to the staff of Admiral George Brydges Rodney as Physician to the Fleet in 1779. Blane was a medical reformer who was convinced by Lind’s original experiment with citrus and appreciated the need for a practical way of storing them. After considerable experimentation, he determined that adding 10 percent “spirits of wine” (i.e., distilled ethyl alcohol) to lemon juice would preserve it almost indefinitely, without destroying its beneficial properties. Like Cook, he did his best to ensure the men under his charge were well provided with fresh vegetables, which delayed scurvy’s onset. But when the first cases finally appeared during a voyage to the Caribbean, he was able to deal with the problem swiftly by administering citrus. Rodney was so impressed with Blane that, when his healthy fleet returned home, he used his considerable influence to have Blane appointed as Commissioner of the Sick and Wounded Board. This enabled Blane to persuade the Admiralty to introduce a daily supplement of lemon juice to sailors’ diet.
From 1795 onward, three-quarters of an ounce of lemon juice per day was mandated to be given to every sailor serving throughout the Royal Navy, nearly banishing scurvy at a stroke. Blane ordered that it be mixed into grog to guarantee its consumption. But the measure came with considerable logistical challenges. In 1804, for example, the Navy Board had to source 50,000 gallons of lemon juice, which typically came from Spanish fruit—and Britain was at war with Spain at the time. As a result, the board switched to lime juice, which could be obtained from British possessions in the Caribbean.
Other navies were slow to adopt similar measures. Some, such as the French, were daunted by the cost and logistical challenges involved in supplying such enormous amounts of fruit. Others, with a ready source of lemons, such as Spain, had a prohibition on giving alcohol to their sailors, which made Blane’s preservation method unacceptable. Still others viewed the Royal Navy’s practice as bizarre. In the War of 1812, U.S. sailors even ridiculed their opponents as “Limeys” (the origin of the term still in use today).
Yet the military benefits of the practice were considerable. During the long war with Napoleonic France, the Royal Navy blockaded much of the coast of Europe—and, from 1812, most of the U.S. coastline, too. This resulted in the fleet expanding to more than 1,000 warships in commission, many remaining at sea for extended periods. Manning such a fleet would have been impossible without a remedy for scurvy.
Controlling the disease delivered considerable tactical benefits, too. At the core of Vice Admiral Horatio Lord Nelson’s forces at the Battle of Trafalgar was the British Mediterranean fleet, which had blockaded the French fleet in Toulon for 22 months prior to the battle. When French forces under Admiral Pierre-Charles Villeneuve finally broke out, they then pursued Nelson out of the Mediterranean, across the Atlantic to the Caribbean, then back to Europe to the waters off Cape Trafalgar in October 1805. Many of the British ships where at sea for most of this time. In a letter home Nelson wrote that he had “spent two years on the Victory, wanting ten days.”
Given this extraordinary period at sea, it should have been the Royal Navy that was decimated by scurvy before the battle, and their opponents (who had been out of port only three months) who were healthy, but the reverse was true. Leonard Gillespie, Nelson’s Physician of the Fleet, reported that the 7,000 men of the Mediterranean fleet had suffered 110 deaths from scurvy and 141 sent to the hospital between 13 August 1803 and 4 August 1805. By contrast, the Spanish commander at Trafalgar, Admiral Federico de Gravina, reported just before the battle that several of his ships had more than 200 scurvy cases each, and one more than 300. The superior health of Royal Navy sailors when compared with their opponents was undoubtedly a major contributor to the victory.