Your troops are surprised and you suffer some losses but you manage to regroup and fortify a camp by nightfall, at which point the skirmish breaks for the day.  You face a formidable army a hundred thousand strong of desperate men fighting for their homeland that you have taken from them. Further conflict is unavoidable. What do you do?  

• Crush them with the full force of your army. The enemy has the advantage in numbers, but you have horses and elephants.
• Fortify your current camp to lead the enemy to believe that you will defend yourself from there on the morrow.  Meanwhile send scouts to see if there is a different place to cross the river to come up behind the barbarians and suprise them the next day.