A war film. The plots are like "Tears of the Sun". Quite sure it's not "First Blood 4".
A troop was protecting a group of weak people from their enemy.
But at the eleven hour, when the troop was being attacked by the enemy, the group of weak people started to protect the troop, and said something like "They once helped us, and now it's our turn to protect them". In the end, the reinforcements arrived, and they turned defeat into victory.