When you are outnumbered, have low forces, and know that you will lose, get a good stand off position by gathering all of your remaining forces, and go to a hill or the highest position if possible. If that is unavailable, go into the forests. Then, gather your forces and put all archers in the very back, all medium to close ranged missile weapons in middle, and all of your spearmen in the front with the legionnaires, swordsmen, etc. just behind. If you have elephants or horses, put them javelins. Then, with the spearmen formation, you can either wait for the enemy to hit the spearmen then charge with horses. However it would be better to horse charge them when they are in archer or javelin range, then keep bombarding them. Next, use all of your swordsmen to attack after the enemy hits the spearmen. Then, use all of your forces to charge, except for the archers. Move them away from the fight and keep bombarding. This is also a good choke point defensive maneuver.