Shall go forth. God is said to "go forth" when he manifests his power by delivering his people and punishing their enemies (comp. Isaiah 26:21; Isaiah 42:13; Micah 1:3). As when he fought in the day of battle.
The Hebrew is in general terms, "as when he fighteth in a day of battle," or, "slaughter;" Septuagint, καθὼς ἡμέρα παρατάξεως αὐτοῦ ἐν ἡμέρα πολέμου, "as a day of his battle in a day of war;" Vulgate, sicut praeliatus est in die certaminis.
There is nothing in the text to confine the reference to any one special interposition; it refers rather to the general course of God's providence in defending his people, though, doubtless, the prophet has in his mind the crowning act of mercy at the Red Sea (Exodus 14:13, Exodus 14:14, Exodus 14:25), which is so often referred to as a typical deliverance (comp.
Isaiah 11:11; Jeremiah 16:14; Jeremiah 23:8; Habakkuk 3:15; and above, Zechariah 10:11).