Against them. — Against the army described in last verse. Literally, unto them (Genesis 4:8; Judges 12:3).
Zerah the Ethiopian. — Heb., ha-Kûshî. (See Note on 1 Chronicles 1:8 [Cush].) Zerah is identified with Osorchon II., hieroglyphic Uasarken, who succeeded Shishak as king of Egypt. The name of this king is curiously like that of Sargon, the great Assyrian conqueror of the eighth century. (See Note on 2 Chronicles 12:2.) The object of the expedition appears to have been to bring Judah again under the yoke of Egypt. Shishak had made Rehoboam tributary (2 Chronicles 12:8), after reducing his fortresses and plundering Jerusalem. But now Asa had restored the defences of his country, and apparently reorganised the fighting material; steps indicating a desire for national independence.
A thousand thousand. — This very large and symmetrical number would probably be best represented in English by an indefinite expression, like “myriads.” It is otherwise out of all proportion to the three hundred chariots, which last seems a correct datum. Syriac and Arabic say “20,000 chariots.”
Mareshah. — One of the fortresses of Rehoboam (2 Chronicles 11:8). It lay in the lowland of Judah, about twenty-six miles south-west of Jerusalem.