Charles Ellicott Commentary 1 Chronicles 11:4-9

"And David and all Israel went to Jerusalem (the same is Jebus); and the Jebusites, the inhabitants of the land, were there. And the inhabitants of Jebus said to David, Thou shalt not come in hither. Nevertheless David took the stronghold of Zion; the same is the city of David. And David said, Whosoever smiteth the Jebusites first shall be chief and captain. And Joab the son of Zeruiah went up first, and was made chief. And David dwelt in the stronghold; therefore they called it the city of David. And he built the city round about, from Millo even round about; and Joab repaired the rest of the city. And David waxed greater and greater; for Jehovah of hosts was with him." — 1 Chronicles 11:4-9 (ASV)

THE CAPTURE OF ZION BY JOAB’S VALOUR, AND DAVID’S SETTLEMENT THERE.

The accession of the new king is followed by a warlike enterprise, according to the precedent of Saul (1 Samuel 11:1). This agrees with the reason assigned for the election of a king (1 Samuel 8:20), as well as with what we know of Assyrian custom, and is a mark of historic truth.