In the narrative of our story (Genesis 14) Chedorlaomer and friends come down from Mesopotamia and conquer Sodom and the surrounding countryside. After thirteen years of servitude, Sodom and the surrounding city states rebel, and Chedorlaomer returns to reconquer them.
The reason the Bible brings this to our attention is that Sodom is the city where Lot lives, and Lot is Abram's nephew. Finding out that Lot is in peril, Abram gathers together 318 of his men and three of his friends and swiftly defeats the army that had rained terror upon the surrounding nations, pursuing it as far as Lebanon.
When we describe Abraham, we usually use words like "faithful" or "hospitable"; "warrior" isn't usually on the list. So what are we supposed to learn from this pericope (a fancy term for Bible passage)?
Some commentators find in it prophesies of the future. Others focus on Abram's refusal to profit from the incident, swearing by God Most High not to "take so much as a thread or a sandal strap of" the spoils (Genesis 14:23). I would like to suggest that it is a reminder that when one's loved ones are in danger, it may be necessary to operate outside of one's comfort zone, and that family will go to the ends of the earth to protect the ones they love.