CODEX Entry 1011: Festival of Zagmuk
This was a twelve-day festival, starting 5 days before the winter solstice, from the 15th December until the 27th December. On the 10th day, 25th December1, the celebration of Marduk’s resurrection would be re-enacted, with the king playing Marduk, and his son, the rescuer Nabu. Having shown Marduk’s resurrection from the underworld, the king would enact the rite of the Sacred Marriage2. During this rite, the king would perform sexual intercourse with a high priestess who had been chosen from among the naditu. Her ritual act of intercourse with the king was believed to regenerate the cosmos through re-enactment of the coupling of their god.
References:
1 Dorothy Morrison, Yule: A Celebration of Light and Warmth
2 Samuel Noah Kramer, The Sacred Marriage Rite