In April 27, 1774, Louis XV of France, then aged 64, felt a little unwell. His head hurt and he felt stiff. Nonetheless, an avid hunter, he decided to go out hunting. Still unwell in the evening he skipped his supper; since he was still ill the next day his doctor ordered that he be transferred from his little palace in Trianon, where he was relaxing with his mistress and some friends, to his bedchamber in Versailles.
The King, still feeling bad, was bled. His doctors surrounded him – and finally, he was diagnosed. “While giving him a drink, red spots were observed on his face. “Bring the candle closer, the King does not see his glass,” said a doctor, standing near by with his colleagues. Everyone recognized the symptoms of smallpox.”
The royal family was kept away, to protect the non-immune heirs against infection. In spite of not being inoculated and not having had the disease, his middle-aged daughters tended him during the day and his youthful mistress, Madame Du Barry, tended him during the night (not at the same time, since the Princesses refused to share the space with the mistress, and she tactfully avoided their presence).
The fever and headaches continued and intensified, and the King’s body was covered in pustules. His head appeared “fort grosse et rouge” – very fat and red. On May 3, the King looked at his hands and realized what he had – smallpox. Frightened for his soul, he asked his mistress, in tears, to leave him the next day.
On May 7, the King called his confessor. In addition to the private confession, the Cardinal de La Roche-Aymon announced in his name that the King “asks forgiveness from God for offending him and for scandalizing his people” and promises to reform if he heals.
The crisis point came on May 8, and after that, the King’s fever rose dramatically. He became delirious and suppuration (discharge of pus) slowed down. On May 9 the pustules were dry and turned black. Pustules and scabs in his throat prevented him from swallowing. His face looked like “a bronze mask with a gaping mouth,” his head black and swollen. The smell was unbearable. His final agony lasted from 11am to 3:15 PM.
That was how Louis XV fell victim to the small pox, a disease that had a 30% mortality rate https://docsimmunize.org/immunize/cdcmanual/original/smallpox.pdf. Soon after his death, his three grandson, led by the new King, Louis XVI, followed the example of the British royal family and inoculated themselves, a process in which the patient was scratched and material from a smallpox lesion put on the wound. Not the safest process. Luckily, in 1796 Edward Jenner invented the first vaccine, the vaccine against smallpox, a much safer procedure (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1200696/). And the rest, as they say, is history.
Simone Bertierre, Marie-Antoinette L’insoumise (2002).