Both Revised Standard Version and Good News Bible insert a paragraph break here, which is appropriate.

After consulting privately with the elders: Judas had a private meeting with the Jewish leaders to discuss his course of action. For elders see the comments on 1Macc 7.33.

He determined to march out and decide the matter by the help of God before the king’s army could enter Judea and get possession of the city: He determined to march out may be rendered “he decided to lead his army out of Jerusalem.” Judas’ strategy was to meet the enemy in battle before they could get near Jerusalem. Decide the matter by the help of God refers to defeating the Syrian army with the help of God.

Here is an alternative model for this verse:

• After this Judas met privately with the Jewish leaders and decided that he would lead his soldiers out of Jerusalem and attack the king’s army. Then [or, In that way], with God’s help, he could defeat the enemy before they entered Judea and captured Jerusalem.

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.