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

Then Simon brought forward his force and engaged the phalanx in battle (for the cavalry was exhausted); they were overwhelmed by him and fled: Translators may find it works well to move the parenthetical expression to the beginning of this verse, as in Good News Bible, to keep events in proper order. The cavalry would have had a problem not only with becoming physically tired, but with running out of arrows (as Josephus specifically says). To begin this verse, For the cavalry was exhausted may be rendered “When the cavalry could fight no longer.” Simon has not been mentioned since verse 74, but if his men were held in reserve during the cavalry attack (as Good News Bible seems to imply with “Simon appeared on the scene with his forces”), the author does not tell us. Presumably his forces were with Jonathan’s all during the battle. For whatever reason, when the cavalry attack weakened, it was Simon’s forces rather than Jonathan’s that regrouped and formed an offensive line of battle to engage the Syrian infantry. For phalanx see the comments on 1Macc 6.35.

An alternative model for this verse is:

• When the Syrian cavalry could fight no longer, Simon brought his men forward and attacked and overpowered the enemy infantry, who [then] fled.

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.