The LORD is a man of war: the LORD is his name. The Lord is a man of war - i:e., a mighty warrior, a resistless conqueror; because all the flower and chivalry of the Egyptian army were destroyed in one moment by his omnipotent arm. The phrase is according to the Hebrew idiom, which uses х 'iysh (H376)] a man, with the genitive of an attribute or quality, as an adjective to denote one to whom that attribute or quality belongs: thus "a man of form" means a handsome man; "a man of blood," a bloody man; "a man of name," a famous man; "a man of words," an eloquent man; "a man of the field," a farmer; and so "a man of war" signifies a great warrior (1 Samuel 17:33). Yahweh is poetically represented as a mighty champion-encountering the foe in the same style of military equipment as the Egyptians-with horses and war-chariot. This same figure is used in an amplified form, with reference to the same historical event, by Habakkuk (Habakkuk 3:8).
The Lord is his name - i:e., according to Scripture usage, His nature: He has now actually shown Himself to be what the name Yahweh implies. The application of this warlike epithet to Yahweh harmonizes with the strain of this triumphant paean, which celebrates the total destruction of a hostile army. Their discomfiture was due solely to the might of Israel's God. There was no room, as there commonly is, after a signal victory, for landing the military skill of the human leader, the gallantry of individual combatants, or the valorous conduct of the people generally. The victory was won solely by "the right arm" of the Lord, and all that the Israelites had to do was to "stand still and see His salvation." This song, therefore, was sung in celebration, not of what God had enabled His people to achieve, but of what He had done for them.