How did April Fools' Day start?

While there are similar holidays in ancient Rome and Britain, the eldest – 

and tidiest – historical reference comes in a Flemish poem from 1561

in which a nobleman sends his servant on "fool's errands" on April 1, 

according to a history of the holiday written by Stephen Winick of the Library of Congress' American Folklife Center.

according to a history of the holiday written by Stephen Winick of the Library of Congress' American Folklife Center.

Roughly the same era in France, people slow to adopt the change of calendar from the last week of March to January 1 –

due to the move from the Julian calendar to the Gregorian calendar, decreed in the Council of Trent – were called "April fools," and were played tricks on, according to History.com.

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