These chapters are still under the section heading titled, David's Wars, according to the Ryrie Study Bible.
Don't Shame the Messenger
This the same story as from II Samuel 10. This incident happens after David has settled the fighting around him and he's has more room for kindness and settling obligations. For example, in Chapter 9 of II Samuel, right before this, David tends to Mephibosheth, Jonathan's son- with whom he had made a covenant. And despite Saul's actions, probably, exonerating David, he had the time and space to settle that.
Likewise, despite being rivals with Ammon, in general, while David was on the run from Saul for 10 years, he needed kindness from many people. And many probably provided it feeling like they were undermining Saul in the process. So, however it happened, David felt like the previous king had showed him kindness and when he passed David wanted to show kindness to his decendant.
Toward this, David sends messengers to bring his consolation.
However, the princes of the sons of Ammon were suspicious that David had sent spies to check out the land toward a plan to overthrow Ammon. So the new king shaved them and cut off their garments to the waist. This is an utter humiliation for a man in their culture. They couldn't even go home until their beards grew back or they would be humiliated.
David got word and had messengers tell them to stay in Jericho until their beards grew back.
When the sons of Ammon realized their mistake; instead of rectifying it, taking responsibility and addressing it head on; they paid for mercenaries from Mesopotamia to bring chariots to the fight. They assembled against David for war.
Joab and the Mighty Men
In return, David sent Joab and the Mighty Men. He picked the strongest side to defend and assigned his brother, Abshai, to contend with the other. They promised to back each others play.
Then Joab did something remarkable. He referred to God. He didn't pray to God or really honor or ask Him for anything; but for Joab, to even consider God while planning seems noteworthy. He said to Abshai:
Be strong and let us show ourselves courageous for the sake of our people and for the cities of our God; and may the Lord do what is good in His sight.Joab, I Chronicles 19:13
Most of the time, as I remember it, Joab refers to God as "your God". For some reason, again, he doesn't pray; but he does acknowledge God as the arbiter of the battle and wants to show courage for God's cities. Interesting.
(Always happy to find a good Joab nugget. I really want to combine all of this together sometime and study him for some reason. He's not a good guy; but he is such a strong figure throughout this time frame.)
The mercenaries fighting Joab fled, then those fighting Abshai fled. They reassembled on the other side of the Jordan. David assembled his army and went after them. He slaughtered almost 50 thousand of them and they made peace with him and served him and never were mercenaries against him again.
Although the fighting stopped for that battle, when the fighting season came back around Joab went after Ammon and "...ravaged the land...".
He besieged the city of Rabbah (modern day Amman, the capital of Jordan). He took their king's crown that weighed 1200 ounces of gold and precious jewels, along with many other spoils of the city. they cut the people with axes and saws and such. They did this in all the cities of Ammon. And then they returned to Jerusalem
David stayed in Jerusalem during this battle. His men had told him to stay away from the fighting; but many speculate that he could have been nearby instead of all the way back in Jerusalem-where he sinned with Bathsheba-ending the golden season of his reign, leading to the murder of Uriah.
The chapter ends with two small passages describing another outbreak with the Philistines and one with Gath.
When I think about the So What? for this passage, it's tough. The good guys do bad things and the bad guys do good things and it's all against the backdrop of a warfare culture we can hardly comprehend in our modern day. We've replaced, "Oh, it's the warfare season!" with "Got to fight these pound so I have a beach bod!"
I think I'm even more curious about Joab from this passage; and I see better the trajectory of David's sin- as he was on a roll. Things were going well and he just came to a stop and went home to his mansion. Maybe he needed to rest. We don't know enough to know for sure. But there was a lot going on for the king to be hanging out his back window checking out the neighbors.
I guess I don't have a good So What for this one. So, I'll simply close with the quote from Joab, making it my prayer today:
"Be strong and let us show ourselves courageous for the sake of our people and for the cities of our God; and may the Lord do what is good in His sight." Amen.