James Leasor's 1961 book "The Plague and the Fire" helps popularize the belief that the children's rhyme is a reference to The Great Plague of 1665-1666 that swept through England (or, by extension, The Black Death of the mid-1300s that devastated Europe). From the book:
Ring a-ring a-roses
A pocketful of poesies,
We all fall down!
Few people watching a group of children dancing hand-in-hand in a circle to this well-known nursery rhyme may realize that it has origin in the plague. Roses refer to the rosy rash of plague, ringed to signify the tokens; the poesies were herbs and spices carried to sweeten the air; sneezing was a common symptom of those close to death. The words "we all fall down" certainly referred to Londoners during that stifling August.
The rhyme, in various versions, dates back to at least the 1700s; it appears in the 1881 book "Mother Goose or the Old Nursery Rhymes" (pictured above).
* "The Plague and the Fire": @
* Article debunking the connection (from snopes.com): @
* "Mother Goose or the Old Nursery Rhymes" (from Project Gutenberg): @
* Summary of The Great Plague (from Harvard University Library): @
* Summary of The Black Death (from Dr. E.L. Skip Knox, Boise State University): @