The ''Great Plague of London'' occurred from 1665 to 1666. Possibly as many as 100,000 persons fell to Bubonic Plague. At the time, The ''Great Plague'' was the last of a series of Epidemics since the 13th Century AD – throughout Europe and portions of Asia. The primary reason for it's emergence was threefold. The first, The City of London had grown to massive size with regards to population, A fast center for trade, commerce etc. - the living condition unfortunately did not advance as fast. No plumbing, lack of consistent sanitation, over-crowding – all played a part in the spread of the deadly disease. The City was measured at only 450-square Acres, surrounded by a Medieval Defensive Wall. The influx of several major riverway resources – meant that a never ending stream of Shipping came inside. From all corners of the ''Known World'', came all manner of goods – and rats. Rats (bourne on Ships from different Ports), carried fleas. Inside the gut of this parasite – was the viral contagion. Given the often horrendous living conditions, the rats soon found homes. Co-habitating with Humans, meant that the fleas could seek new Hosts and spread The Plague.
Medicine was still quite superstitious with regards to ''what'' caused The Disease. Often, herbs, blood letting and of course prayers were the only relief that could be given. Whole neighborhoods fell dead within 7-days of Bubonic exposure. The corpses of the victims proved too much for the average Church Cemetery. Often, bodies would remain where they fell – for days, decomposing. This too added to the contagion's effectiveness. But a cure was found, in the most unlikely of means. That means was fire....and by accident. The ''Great London Fire of 1666'' spread throughout The City. The crude Tudor-Era structures of wood would catch fire and spread from building to building (very few stone structures existed then). Thousands upon thousands lost all they had and were homeless. But it was noticed in this tragedy, that The Plague had stopped. Why? The fire not only sterilized locations, it killed both rodent and flea. It also gave way to the popular notion of cremating Plague Victim bodies, despite the outrage of The Church against such Acts. The Great Plague of 1665-1666 would be the last such major outbreak of Bubonic contagion in London. Slightly better City Planning was developed (although true City development and proper accommodations, as well as major advances in Medicine and care would be several Centuries yet away).