Yule.

In De temporum ratione, a book by by Bede, attempting to make sense of the calendar; Bede writes that the pagan Anglo-Saxons:

...began the year on the 8th kalends of January [25 December], when we celebrate the birth of the Lord. That very night, which we hold so sacred, they used to call by the heathen word Modranecht, that is, "mother's night", because (we suspect) of the ceremonies they enacted all that night.

Feasting means the shedding of animal blót.
Blood.

Lots of it.

The Scandinavian dísablót is associated with the Anglo-Saxon modranect ("mothers' night") by Gabriel Turville-Petre (in Myth and Religion of the North (1964). And the modranect was probably only a part of the festival we recall as Yule.

Yule is a Middle English word, probably a preservation of an Angle-Saxon word.

The "Anglii" were first mentioned by name by the Roman historian Tacitus in his book "Germania" written in AD 98.  and the Anglo-Saxons are described as the descendent of the three tribes of Germanic immigrants (the Jutes, the Angles, and the Saxons) to the island of Britain in the 5th century.

But in the 7th century .

The Gregorian mission (or Augustinian mission) was sent by Pope Gregory the Great in 596 AD to convert Britain's Anglo-Saxons to Christianity. Headed by Augustine of Canterbury, by the death of the last missionary in 635 the mission had established Christianity in southern Britain. Along with the Irish and Frankish missions it converted other parts of Britain as well and influenced the Hiberno-Scottish missions to Continental Europe. Continue...

Iceland seems the best place to go to study what is left of a pre-Christian festival: 

A celebration of the winter solstice has been held since time immemorial in the Northern Hemisphere. Throughout the ages the festival has had many names. It is certain that a mid-winter festival called Yule was celebrated in the Nordic countries well before the year 1000.
Though challenged by some scholars, the fact that Yule/Jól was celebrated here in Iceland and throughout the Northern Hemisphere well before the advent of Christianity is now widely accepted. The exact date, or dates, that Yule was celebrated is not certain, but it was probably connected to the full moon nearest the winter solstice. The calendar has been changed many times since, and it is impossible to reconcile the references to an exact date.
The name itself has been retained in many languages--
Yule - Jól - Jul
even if the cause for celebration has shifted from the sun reversing its downward path, shining ever longer each day, to the birth of Jesus. This linguistic retention of the name should be proof enough that the festival has always been an important one. For close to a thousand years people have tried to explain the meaning of the name "Yule" to no avail. Some scholars believe it comes from one of the names of Óðinn, others have even theorized that it came from the name of Julius Caesar. It has also been suggested that Jól is derived from the Old-Nordic word for wheel: Hjól, the theory being that the wheel of the year has come full circle, and this is just the tip of the iceberg. There have been more attempts at explanations than one can shake a stick at. Certainly the exact meaning of the original word is something we shall never know. Continue...

The solstice sun changes its rise and set positions slower than the equinox sun. The sun rises at an azimuth of 129 and sets at 231 for three whole weeks- December 11th until December 21st.

Sun set begins to happen latter, from December 18th
Sunrise begins to be earlier from January the 5th.