C. F. Keil and Franz Delitzsch on 2 Chronicles 14:8

2Ch 14:8 The victory over the Cushite Zerah. - 2Ch 14:8. “And there went forth against them Zerah.” אליהם for עליהם refers to Asa’s warriors mentioned in 2Ch 14:7. The number of the men in Judah capable of bearing arms is mentioned only to show that Asa set his hope of victory over the innumerable host of the Cushites not on the strength of his army, but on the all-powerful help of the Lord (2Ch 14:10). The Cushite זרח is usually identified with the second king of the 22nd (Bubastitic) dynasty, Osorchon I; while Brugsch, hist. de l'Eg. i. p. 298, on the contrary, has raised objections, and holds Zerah to be an Ethiopian and not an Egyptian prince, who in the reign of Takeloth I, about 944 b.c., probably marched through Egypt as a conqueror (cf. G. Rösch in Herz.'s Realenc. xviii. S. 460). The statement as to Zerah’s army, that it numbered 1,000,000 warriors and 300 war-chariots, rests upon a rough estimate, in which 1000 times 1000 expresses the idea of the greatest possible number. The Cushites pressed forward to Mareshah, i.e., Marissa, between Hebron and Ashdod (see on 2Ch 11:8).