Following the British Calendar Act of 1751, Britain adopted the Gregorian Calendar in 1752. However, the current Julian calendar system required them to drop eleven days in order to sync themselves with the proposed Gregorian Calendar.
It was instituted in 1582 by Pope Gregory XIII, after whom the calendar was named, by papal bull Inter gravissimas dated 24 February 1582. The motivation for the adjustment was to bring the date for the celebration of Easter to the time of year in which it was celebrated when it was introduced by the early Church.
Apr 28, 2017 - Today, Americans are used to a calendar with a "year" based the earth's rotation ... no relationship to the cycles of the moon and New Years Day falling on January 1. ... However, no adjustments were made to compensate.