As sailors began to explore the world and leave land further astern, the problem of keeping healthy on long voyages became acute. Malnourishment and crowded conditions bred disease, and serious injury was commonplace. As navies developed the well being of crews became a dominant factor in the success of naval operations. It is no surprise that the Royal Navy led the way in shipboard medical provision and sponsored many of the advances in diet and hygiene which, by the Napoleonic Wars, gave its fleets a significant advantage over all its enemies; these improvements trickled down to the merchant service.

Kevin Brown, the author, is the curator of the Alexander Fleming Museum at St mary's Hospital, Paddington and an expert in the history of medicine.