Now, therefore, assemble the rest of the troops, lay siege to the city, and capture it. Otherwise I will capture the city, and it will be named after me.”
We have here an account of the conquest of Rabbah, and other cities of the Ammonites. Though this comes in here after the birth of David's child, yet it is most probable that it was effected a good while before, and soon after the death of Uriah, perhaps during the days of Bath-sheba's mourning for him. Observe, 1.
Commenting on 2 Samuel 12:26-31
And David gathered all the people together,.... The soldiers that were with him, or near him; which was done partly to recruit Joab's troops, who, by the continuance of the siege, and the sallies of the enemy on them, might be greatly diminished; and partly to make conquests of other cities of the Ammonites, and to carry off the spoil of them: and went to...
encamp against the city, and take it--It has always been characteristic of Oriental despots to monopolize military honors; and as the ancient world knew nothing of the modern refinement of kings gaining victories by their generals, so Joab sent for David to command the final assault in person. A large force was levied for the purpose.