The Great Plague of London Kills a Quarter of the City
London's last major plague outbreak fills parish death registers faster than clerks can count, and DNA confirms the cause only in 2016
Quick facts
- Pathogen
- Yersinia pestis, confirmed by DNA analysis in 2016
- Duration
- 1665 to 1666
- Official recorded toll
- 68,596 deaths in parish Bills of Mortality; true toll likely over 100,000
- Share of population
- About 15% of London's roughly 460,000 residents
- Peak week
- 7,165 deaths in a single week in September 1665
What happened
Plague cases first appeared in the parish of St Giles-in-the-Fields, just outside London's city walls, in the spring of 1665, and mortality rose through the summer heat to peak in September, when 7,165 Londoners died of plague in a single week according to parish Bills of Mortality. Officially recorded deaths reached 68,596, but the true toll is thought to have exceeded 100,000, roughly 15 percent of the city's population of about 460,000, since the bills excluded Quakers, Anabaptists, and Jews and often misattributed cause of death. Victims suffered fever, headache, vomiting, and the swollen, blackened lymph nodes known as buboes; untreated bubonic plague killed roughly 30 percent of those infected within about two weeks, while the rarer pneumonic and septicemic forms were nearly always fatal.
Why it matters
This was the last severe outbreak of the Second Plague Pandemic in England. The epidemic finally faded with the onset of cold weather, and historians now credit a combination of rising rat and human resistance and tighter maritime quarantine rather than the Great Fire of London the following year, which mostly missed the poorer parishes where plague deaths concentrated. Bubonic plague did not vanish from England after 1666, but no outbreak on this scale recurred.
How we know
Weekly parish Bills of Mortality provide a contemporary statistical record, though an incomplete one given known undercounting. The disease was long assumed to be Yersinia pestis based on symptoms and historical pattern, but this was only confirmed by direct DNA analysis of plague-pit remains in 2016.
Sources
- The National Archives (UK). Great Plague of 1665-1666 · Primary source (author-declared)nationalarchives.gov.uk · Cited as a "primary" source (no stronger domain match). · Link is live and its text matches the event's key terms (Jul 2026)
- The National Archives (UK). Great Plague of 1665-1666 · Reputable sourcenationalarchives.gov.uk · The domain "nationalarchives.gov.uk" is on our Reputable source registry. · Link is live and its text matches the event's key terms (Jul 2026)
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