The already-rebellious prisoners being escorted to Zarahemla launch a suicide mission, at least for those in the front ranks, to break out of the encircling guards. Gid reports that the Nephites cut down more Lamanites than escaped, a possibly favorable interpretation of what happened. It would not be surprising if the escapees were more numerous than the dead since those who were unengaged in combat might simply move past those who were so engaged.
This combination of slaughter and escape removed Gid’s first duty—to guard the prisoners to Zarahemla—leaving his unit free to return to Judea. The Lamanites who escaped would have gone south toward the land of Nephi. While this route would have taken them past the now-Nephite controlled cities of Judea and Cumeni, they would have taken pains to avoid those cities.
When Gid’s men learned about the attack on Helaman’s army, they could march faster and fight more freely. Even though the loss of the prisoners was not ideal, it resulted in preserving Helaman’s army.