Charles Ellicott Commentary 2 Chronicles 17:19

"These were they that waited on the king, besides those whom the king put in the fortified cities throughout all Judah." — 2 Chronicles 17:19 (ASV)

These waited on the king. —Rather, these are those who ministered to the king, namely, the five generals named above.

Beside those whom the king put in the fenced cities —that is, the commandants of the fortresses of the kingdom (2 Chronicles 11:11; 2 Chronicles 11:23). These latter, as well as the generals of the forces, are called the king’s “ministers” (mĕshârĕthîm)—a word which is not used of service in the field, but implies their presence at court (“in Jerusalem,” 2 Chronicles 17:13, as the royal staff).

According to the list above, the army of Jehoshaphat was organized in five grand divisions, corresponding perhaps to five territorial divisions of the southern kingdom. The totals are the largest assigned to the two tribes anywhere in the Old Testament; namely, Judah 780,000, and Benjamin 380,000; in all, 1,160,000. At David’s census Judah had 500,000 warriors (2 Samuel 24:9), and Israel 800,000.

Again, in 2 Chronicles 14:8, Asa’s army consists of 300,000 men of Judah and 280,000 Benjaminites: clearly, such an increase as our text indicates is unaccountable. At the same time, it is equally clear that the present numbers are not fortuitous results of clerical errors, for they follow each other in the order of relative strength: Judah, 300,000, 280,000, 200,000; Benjamin, 200,000, 180,000. They are evidently not independent of the estimates of 2 Chronicles 14:8 quoted above.

In the absence of adequate data for modifying these certainly startling figures, it is well to bear in mind that we need not understand them as an army that ever actually mustered in the field or on parade. They might instead be an estimate of the total male population liable to be called out for the national defense. Even with that understanding, however, the total appears to be at least three times too great, considering the small extent of the country.