The Julian calendar is put into effect for the first time. It was introduced by Julius Caesar to replace the previous Roman calendar which had fallen terribly out of date. For example, Caesar crossed the Rubicon on January 10, 49 BC according to the  Roman calendar, when in reality it was actually mid-autumn. Although the Julian calendar was a vast improvement over the previous calendar, the astronomical solstices and equinoxes would advance by about 11 minutes each year. This caused the calculated date of Easter to slide further and further away from the March equinox. In 1582, Pope Gregory declared that the Gregorian Calendar, which had a reduced number of leap years to compensate for the 11-minute drift, would replace the Julian. If the Julian calendar was still in use, today’s date would be January 14th.