My suggestion would be as follows -
Farmers, Bandits (all non enlisted)
If outnumbered 5 to 1, will offer gold to survive
if outnumbered 10 to one, will surrender and become your prisoners
Caravans
If outnumbered 3 to 1, will offer gold for survival
If outnumbered 5 to 1, will offer some recourses and gold for survival
if outnumbered 12 to 1, will surrender
Regular Armies
If outnumbered 5 to one, will offer gold
if outnumbered 10 to one, will fight heroically
if outnumbered 15 to one, will surrender