So all the army assembled and they went up to Mount Zion: The army refers to the men who had fought alongside of Judas. It is not clear whether the men had dispersed since the last battle, or whether they were still together, but here simply began their march to Jerusalem. Mount Zion is the hill in Jerusalem where the Temple stood. An alternative model for this verse is

• So Judas assembled all the soldiers and they went [up] to Mount Zion.

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.