In Chaucer's Canterbury Tales (1392), the "Nun's Priest's Tale" is set Syn March bigan thritty dayes and two. Chaucer probably meant 32 days after March, i.e. May 2, the anniversary of the engagement of King Richard II of England to Anne of Bohemia, which took place in 1381. However, readers apparently misunderstood this line to mean "March 32," i.e April 1. In Chaucer's tale, the vain **** Chauntecler is tricked by a fox.
In 1508, a French poet referred to a poisson d’avril (April fool, literally "April fish"), a possible reference to the holiday. In 1539, Flemish poet Eduard de Dene wrote of a nobleman who sent his servants on foolish errands on April 1. In 1686, John Aubrey referred to the holiday as "Fooles holy day", the first British reference. On April 1, 1698, several people were tricked into going to the Tower of London to "see the Lions washed." The name "April Fools" echoes that of the Feast of Fools, a Medieval holiday held on December 28.
In the Middle Ages, New Year's Day was celebrated on March 25 in most European towns. In some areas of France, New Year's was a week-long holiday ending on April 1. So it is possible that April Fools originated because those who celebrated on January 1 made fun of those who celebrated on other dates. The use of January 1 as New Year's Day was common in France by the mid-sixteenth century, and this date was adopted officially in 1564 by the Edict of Roussillon.
In the eighteenth century the festival was often posited as going back to the time of Noah. According to an English newspaper article published in 1789, the day had its origin when Noah sent his dove off too early, before the waters had receded; he did this on the first day of the Hebrew month that corresponds with April.