Verse 2 begins the prophecy. During his triumphal reign, Yahweh commands Israel to raise a banner on a high mountain where it will be easily seen to warn the world. Each nation had a different form of standard, but each was some insignia or banner attached to a tall pole. The movements of the troops were made visible by the progress of these standards. Among Israel, the standards were typically banners attached to the poles. While these standards were still standing, the nation was still fighting. The falling of the standard symbolized defeat. In the Roman army, the standard bearer held a sacred obligation. Edward Gibbons observes:
On his first entrance into the service, an oath was administered to him with every circumstance of solemnity. He promised never to desert his standard, to submit his own will to the commands of his leaders, and to sacrifice his life for the safety of the emperor and the empire. The attachment of the Roman troops to their standards was inspired by the united influence of religion and of honor. The golden eagle, which glittered in the front of the legion, was the object of their fondest devotion; nor was it esteemed less impious than it was ignominious, to abandon that sacred ensign in the hour of danger.
The banner in the high mountain declared the triumphant Messiah’s return to his people. His presence is no secret. Rather “exalt the voice” is the aural equivalent of the ensign. Israel will warn the world, both by its physical presence and by direct communication, that Yahweh is among them, fighting their battles.
Blenkinsopp translates the next command as: “Wave your hand for them to enter the princely gates.” This translation makes the entire opening section an invitation, welcoming those who are attracted to the ensign. They will be treated as though they are of the highest rank (allowed to enter the “princely gates”), regardless of their actual social standing. This egalitarian invitation to the city of God is the intent of many of Isaiah’s prophecies of the future (such as Isa. 2).