century. It was likely discovered in China in the 16th century and was widely practiced by the Ottomans and on the Indian subcontinent, at least by the wealthy and/or educated. The procedure was to draw a pin across an oozing smallpox pustule, then stick it into several people . This gave them the virus but with such a small initial viral load that the case was usually mild. Full blown smallpox kiled about 30%. Inoculation smallpox killed about 2%. So while this is icky doodle to us, it was cutting edge medicine that saved huge numbers of people.

Eventually Jenner discovered that cowpox immunity prevented people from catching smallpox and vaccination was born.

While this soldier was ill enough to be grumpy about it, his danger of death was quite small for the time. I imagine the fishing trip infected his pox, giving him the boils, along with infecting him with the amoebas that cause dysentery. So I hope he really enjoyed breaking quarantine to go fishing because it cost him later.