By a grand metaphor the invading army is compared to the sea.

The sea is come up - A multitude of foes have inundated the city.

The sea is come up upon Babylon,.... A vast army, comparable to the great sea for the multitude thereof, even the army of the Medes and Persians under Cyrus; so the Targum,

"a king with his armies, which are numerous like the waters of the sea, is come up against Babylon:''

she is covered with the multitude of the waves thereof; being surrounded, besieged, surprised, and seized upon by the multitude of soldiers in that army, which poured in upon it unawares. Some think here is a beautiful antithesis, between the inundation of Cyrus's army and the draining of the river Euphrates, by which means he poured in his forces into Babylon.

Description of the fall. The sea that has come over Babylon and covered it with its waves, was taken figuratively, even by the Chaldee paraphrasts, and understood as meaning the hostile army that overwhelms the land with its hosts. Only J. D. Michaelis was inclined to take the words in their proper meaning, and understood them as referring to the inundation of Babylon by the Euphrates in August and in winter. But however true it may be, that, in consequence of the destruction or decay of the great river-walls built by Nebuchadnezzar, the Euphrates may inundate the city of Babylon when it wells into a flood, yet the literal acceptation of the words is unwarranted, for the simple reason that they do not speak of any momentary or temporary inundation, and that, because Babylon is to be covered with water, the cities of Babylonia are to become an arid steppe. The sea is therefore the sea of nations, cf. Jeremiah 46:7; the description reminds us of the destruction of Pharaoh and his host in the Red Sea. On Jeremiah 51:43, cf. Jeremiah 48:9; Jeremiah 49:18, Jeremiah 49:33., Jeremiah 50:12. The suffix in בּהן refers to "her cities;" but the repetition of ארץ is not for that reason wrong, as Graf thinks, but is to be explained on the ground that the cities of Babylonia are compared to a barren land; and the idea is properly this: The cities become an arid country of steppes, a land in whose cities nobody can dwell.

The {z} sea is come up upon Babylon: she is covered with the multitude of its waves.

(z) The great army of the Medes and Persians.

51:42 The sea - A multitude of enemies.

42. The sea-the host of Median invaders. The image (compare Jer 47:2; Isa 8:7, 8) is appropriately taken from the Euphrates, which, overflowing in spring, is like a "sea" near Babylon (Jer 51:13, 32, 36).

51:1-58 The particulars of this prophecy are dispersed and interwoven, and the same things left and returned to again. Babylon is abundant in treasures, yet neither her waters nor her wealth shall secure her. Destruction comes when they did not think of it. Wherever we are, in the greatest depths, at the greatest distances, we are to remember the Lord our God; and in the times of the greatest fears and hopes, it is most needful to remember the Lord. The feeling excited by Babylon's fall is the same with the New Testament Babylon, Re 18:9,19. The ruin of all who support idolatry, infidelity, and superstition, is needful for the revival of true godliness; and the threatening prophecies of Scripture yield comfort in this view. The great seat of antichristian tyranny, idolatry, and superstition, the persecutor of true Christians, is as certainly doomed to destruction as ancient Babylon. Then will vast multitudes mourn for sin, and seek the Lord. Then will the lost sheep of the house of Israel be brought back to the fold of the good Shepherd, and stray no more. And the exact fulfilment of these ancient prophecies encourages us to faith in all the promises and prophecies of the sacred Scriptures.