Translators may insert a paragraph break here (so Revised Standard Version).

On the monthly celebration of the king’s birthday: The king’s birthday was celebrated once every month. In languages that do not have the passive voice, translators may say “Each month, the foreigners celebrated the king’s birthday” (Contemporary English Version).

The Jews were taken, under bitter constraint, to partake of the sacrifices: During the celebration of the king’s birthday each month the Gentiles sacrificed animals, and the Jews were forced to eat the meat from these animals that had been sacrificed to Greek gods. Partake refers to eating. The Jews were taken, under bitter constraint, to partake of … may be rendered “the Jews were cruelly forced to eat…,” “the Jews were compelled by brute force to eat…” (Good News Bible), or even “the Gentiles cruelly [or, brutally] forced the Jews to eat….” The Greek word translated sacrifices refers literally to the internal organs of the animals, which were eaten first. This word includes the “intestines” (Good News Bible), the heart, the lungs, the liver, and other internal organs, so it may be rendered “insides” or “inner organs.” In Jewish sacrifices these portions were usually burned, not eaten. The point is not that the Jews were compelled to eat disgusting food, but that they were forced to eat meat from animals that were sacrificed to Greek gods.

And when the feast of Dionysus came: The connector and may be rendered “Besides this” (Contemporary English Version). The feast of Dionysus was celebrated at least once a year, sometimes twice. It was a festival in honor of the god of wine, Dionysus. Good News Bible provides a helpful model here, saying “Then, during the festival in honor of the wine god Dionysus.”

They were compelled to walk in the procession in honor of Dionysus, wearing wreaths of ivy: People celebrating the festival wore wreaths of ivy on their heads. Ivy was a sacred plant used in the worship of Dionysus. The Jews were forced to honor this Greek god by wearing wreaths (or, garlands) woven out of sprigs of ivy on their heads.

A model for the second half of this verse is:

• Besides this, during the festival when they honored the wine god Dionysus, the foreigners [or, Gentiles] forced the Jews to walk in parades wearing wreaths [or, garlands] made from ivy on their heads.

Quoted with permission from Bullard, Roger A. and Hatton, Howard A. A Handbook on 1-2 Maccabees. (UBS Helps for Translators). New York: UBS, 2011. For this and other handbooks for translators see here.