So Judas decided to destroy them: The connector So indicates that Judas’ decision came as a result of what the enemies in the fort were doing. For decided to destroy them, Good News Bible has “decided to get rid of them” and Contemporary English Version says “decided to … get rid of those troublemakers.”

And assembled all the people to besiege them: All the people here presumably refers to the able-bodied men of the Jewish community. This clause may be rendered “and gathered together all his soldiers to besiege [or, surround] the fort.”

They gathered together and besieged the citadel in the one hundred and fiftieth year: Verses 19-20 may be combined since this clause and the previous one describe the same event, so they are redundant (see the model below). The one hundred and fiftieth year corresponds to 162 b.c. (see the comments on 1Macc 1.10).

And he built siege towers and other engines of war: For siege towers and engines of war, see the comments on 1Macc 5.30.

A model that combines verses 19-20 is.

• So Judas decided to get rid of these troublemakers, and called his soldiers together. They began a siege of [or, surrounded] the fort in the year 150. They built siege platforms and other weapons of war to capture the fort.

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.