1Chronicles 20:1 ¶ And it came to pass, that after the year was expired, at the time that kings go out to battle, Joab led forth the power of the army, and wasted the country of the children of Ammon, and came and besieged Rabbah. But David tarried at Jerusalem. And Joab smote Rabbah, and destroyed it.
The opening verse indicates a continuation of the narrative from the previous chapter.
David did not go to seek retribution against Ammon right away; he waited until the year had expired, until the season changed (to Spring), and the weather was once again conducive to fighting battles with the enemy.
The NIV Commentary provides this insight: “Springtime, which marks the end of the rainy season in the Middle East, assures that roads will be in good condition (or at least passable), that there will be plenty of fodder for war horses and pack animals, and that an army on the march will be able to raid the fields for food.”
Instead of leading his men in battle, as was expected by custom, David sent his army out under the command of Joab, his military commander; but he stayed in Jerusalem. Their purpose—to destroy the children of Ammon and set siege to Rabbah, the capital city (current day Amman), about 40 miles east of Jerusalem.
Sadly, it is noted in the record in Samuel that it was during this time that David committed his sin with Bathsheba and ultimately ordered the murder of Uriah, her husband.
The troops of Israel led by Joab eventually attacked Rabbah and destroyed it.
The record in 2Samuel adds a bit more.
2 Samuel 12:27–29 “And Joab sent messengers to David, and said, I have fought against Rabbah, and have taken the city of waters. Now therefore gather the rest of the people together, and encamp against the city, and take it: lest I take the city, and it be called after my name. And David gathered all the people together, and went to Rabbah, and fought against it, and took it.”
The troops of Israel, under Joab’s leadership, had essentially conquered Rabbah, the capital city of Ammon. He sent word to inform David and urged him to gather the rest of his troops and come and join him on the battlefield before Joab was given all the credit and the conquered city named after him.
JFB has a comment that helps explain the reference to “the city of waters.”
“Rabbah, like Aroer, was divided into two parts — one the lower town, insulated by the winding course of the Jabbok, which flowed almost round it, and the upper and stronger town, called the royal city. “The first was taken by Joab, but the honor of capturing so strongly a fortified place as the other was an honor reserved for the king himself.”
1Chronicles 20:2 And David took the crown of their king from off his head, and found it to weigh a talent of gold, and there were precious stones in it; and it was set upon David’s head: and he brought also exceeding much spoil out of the city.
1Chronicles 20:3 And he brought out the people that were in it, and cut them with saws, and with harrows of iron, and with axes. Even so dealt David with all the cities of the children of Ammon. And David and all the people returned to Jerusalem.
David followed Joab’s advice and joined the battle, eventually taking possession of the whole city. He took the king’s crown off the head of Ammon’s king, a crown that was made from a talent of gold and was embedded with precious stones. The crown was placed on David’s head, and his men gathered a great amount of treasure from the city as the spoils of victory.
According to the available information, this crown would have been too heavy for David to wear if it actually weighed a talent of gold. Commentators note that it weighed between 75-125 pounds. JFB states, “…like many other state crowns of Eastern kings, the crown got at Rabbah was not worn on the head, but suspended by chains of gold above the throne.”
I think the main point is that the crown was very valuable and became David’s by right of conquest.
I liked the ESV translation of Again, we learn more from the book of Samuel: I liked the ESV translation - 2Samuel 12:31 “And he brought out the people who were in it and set them to labor with saws and iron picks and axes. And thus David did to all the cities of the Ammonites. Then David and all the people returned to Jerusalem.”
1Chronicles 20:4 ¶ And it came to pass after this, that there arose war at Gezer with the Philistines; at which time Sibbechai the Hushathite slew Sippai, that was of the children of the giant: and they were subdued.
1Chronicles 20:5 And there was war again with the Philistines; and Elhanan the son of Jair slew Lahmi the brother of Goliath the Gittite, whose spear staff was like a weaver’s beam.
1Chronicles 20:6 And yet again there was war at Gath, where was a man of great stature, whose fingers and toes were four and twenty, six on each hand, and six on each foot: and he also was the son of the giant.
1Chronicles 20:7 But when he defied Israel, Jonathan the son of Shimea David’s brother slew him.
1Chronicles 20:8 These were born unto the giant in Gath; and they fell by the hand of David, and by the hand of his servants.
Some time later a war developed at Gezer against the Philistines. During this battle, from which they emerged victorious, Sibbechai the Hushathite killed Sippai, one of the children of the giant.
Yet another battle against the Philistines occurred in which Elhanan, son of Jair, killed Lahmi, the brother of Goliath the Gittite, the giant David killed with his sling. Like his brother before him, Lahmi carried a great spear like a weaver’s beam.
In yet another battle at Gath, there was a very tall man that had six fingers on each hand and six toes on each foot, another son oof the giant. When he came out to defy Israel, Jonathan, son of Shimea (David’s brother), killed him.
Verse 8 seems to imply that “the giant” referenced in verses 4 and 6 is Goliath.
Guzik made an interesting application on verse 8 “they fell by the hand of David” – “Part of the idea is that David is conquering enemies now so it will be better for Solomon in the future. Our present victory is not only good for us now but it passes something important on to the next generation.”