1 Chronicles 20:1

after the year was expired R.V. at the time of the return of the year, i.e. in the spring, 2Sa 11:1; 1 Kings 20:22.

the power of the army The Heb. phrase is quite general in meaning: the host of war, the military forces.

Rabbah the capital of the Ammonites; Jeremiah 49:2; Ezekiel 21:20 (25, Heb). Its site, now called - Ammân, is covered with important ruins of the Roman and Byzantine periods. The town lies in a fertile basin, its citadel on a hill on the north side. Bädeker, pp. 185 ff.

David tarried at Jerusalem In 2 Sam. these words introduce the story of David's adultery with Bath-sheba, which is omitted from Chron.

Joab smote Rabbah In 2 Samuel 12:27 Joab reports to David the capture of the city of waters(i.e. the lower city), and invites him to come and complete the conquest (presumably by capturing the citadel) in person. Probably the citadel was dependent for water on the river which lows through the town.