BRUMALIA

In the Roman Empire on the great day of December 25th, came the Brumalia or festival of the shortest day.
It was a day of great religious significance for the sun-worshipers.
This day was also known as Natalis Solus Invicti or the "Birth of the Unconquerable Sun"
This was the time when the day began again to lengthen.
In the fifth century the Western Church ordered Christmas to be celebrated forever on the day of the old Roman feast of the birth of Sol.