April fools day began many years ago in france. what event started it

It is believed that the tradition of celebrating April fools' day began approximately in the mid sixteenth century when France (upon the directive of Pope Gregory XIII) abandoned the Julian calendar in favor of the Gregorian calendar. Use of this new calendar meant that the new year would now begin on the first day of January as opposed to the first day of April. Those who did not catch this news in time went on celebrating the beginning of the new year on April 1st and as such they were ridiculed  and made the laughing stock on this account. These people would henceforth be referred to as 'April fools'.