The War of the 4 Kings vs the 5 Kings

Breishit ch 14 contains an interesting story about how Lot, the nephew of Avraham was taken captive.  I think that a lot of people particularly students miss the point of the story.  I see the story as having two main learning points.  The first is that Avraham will do the right thing and go to any length to rescue Lot, a close relative.  This also brings up a different question about Yishmael.  Avraham is for most commentators a paradigm of Chessed(kindness).  Yet he ejects Yishmael from his home with only bread and water.  The reasons given by the commentators such as that he was following G-ds command to listen to Sarah who told him to get Yishmael out of the house, are wholly unsatisfying.  I have no good answer for this problem.  But I digress.  Getting back to Avraham and the war of the 5 kings versus the 4 kings, one must understand the geopolitics of the time and place in order to understand the story.  This was asymmetric warfare.. There is no question that the Torah is pointing this out.  The identification of the kings from the northeastern area with historical figures such as Hammurabi is uncertain, but the name of the kingdom is not uncertain.  Shinar and Elam  and Elasar(probably Larsa) are powerful entities.  Shinar is the closest thing to an empire at the time.  The others might be vassals which under treaty would be obligated to fight for their master.  The Torah goes on to mention that the 4 kings defeated the aboriginal inhabitants such as Emim, Rephaim and Zuzim and Amalek and the Amorites.  The five kings on the other hand were vassals to the four kings.  They ruled over small city states in Canaan.  So basically this war would be akin to the 1927 Yankees playing against my grandsons little league team.  With that as background the Torah narrates a story which should be seen in a different light than simply a war of two opposing forces. Avraham mobilizes his 318 men and defeats one of the most powerful fighting forces of his day.
  One further thought.  During the late bronze age  1500- 1200 BCE, Canaan is a  vassal to Egypt. Circumstances alluding to this fact are sparse or absent in the Torah.  If we date Avraham to between 1700 or 1600 BCE, It may be that there were times when the Mesopotamians held sway over Canaan during Avrahams lifetime.