And I will camp against thee round about. By the word kdvr (kaddur) [1] he alludes to the roundness of a ball; and the expression corresponds to one commonly used, ("Je l'environneray,") "I shall surround it." Thus he shews that all means of escape will be cut off. And will lay siege against thee. This alludes to another method of invading the city; for either attacks are made at various points, or there is a regular siege. He confirms the doctrine of the former verse, and shews that this war will be carried on under God's direction, and that the Assyrians, though they are hurried on by their passions and by the lust of power, will undertake nothing but by the command of God. He reckoned it to be of great importance to carry full conviction to the minds of the Jews, that all the evils which befell them were sent by God, that they might thus be led to enter into an examination of their crimes. As this doctrine is often found in the Scriptures, it ought to be the more carefully impressed on our minds; for it is not without good reason that it is so frequently repeated and inculcated by the Holy Spirit.

Footnotes

1 - "Like a circle of tents. ndvr, (kaddur,) like a Dowar; so the Arabs call a circular village of tents, such as they still live in." -- Stock

And I will camp against thee - That is, I will cause an army to pitch their tents there for a siege. God regards the armies which he would employ as under his control, and speaks of them as if he would do it himself (see the note at Isaiah 10:5).
Round about - (כדוּר kadûr). As in a circle; that is, he would encompass or encircle the city. The word used here דור dûr in Isaiah 22:18, means a ball, but here it evidently means a circle; and the sense is, that the army of the besiegers would encompass the city. A similar form of expression occurs in regard to Jerusalem in Luke 19:43 : 'For the days shall come upon thee, than thine enemies shall cast a trench (χάρακα charaka - "a rampart," a "mound") about thee σοί soi "against thee"), and "compass thee round" περικυκλώτονσί σε perikuklōsousi se, "encircle thee").' So also Luke 21:20. The Septuagint renders this, 'I will encompass thee as David did;' evidently reading it as if it were כדוּד kadûd; and Lowth observes that two manuscripts thus read it, and he himself adopts it. But the authority for correcting the Hebrew text in this way is not sufficient, nor is it necessary. The idea in the present reading is a clear one, and evidently means that the armies of Sennacherib would encompass the city.
With a mount - A rampart; a fortification. Or, rather, perhaps, the word מצב mutsâb means a post, a military station, from יצב yâtsab, "to place, to station." The word in this form occurs nowhere else in the Scriptures, but the word מצב matsâb occurs in 1-Samuel 13:23; 1-Samuel 14:1, 1-Samuel 14:4; 2-Samuel 23:14, in the sense of a military post, or garrison.
I will rise forts - That is, ramparts, such as were usually thrown up against a besieged city, meaning that it should be subjected to the regular process of a siege. The Septuagint reads, Πύργου Purgou; 'Towers;' and so also two manuscripts by changing the Hebrew letter ד (d) into the Hebrew letter ר (r). But there is no necessity for altering the Hebrew text. Lowth prefers the reading of the Septuagint.

And I will camp against thee round about "And I will encamp against thee like David" - For כדור caddur, some kind of military engine, כדוד kedavid, like David, is the reading of the Septuagint, two MSS. of Kennicott's, if not two more: but though Bishop Lowth adopts this reading, I think it harsh and unnecessary.
Forts "Towers" - For מצרת metsuroth, read מצדות metsudoth: so the Septuagint and five MSS. of Dr. Kennicott's, one of them ancient, and four of De Rossi's.

And I will camp against thee round about,.... Or as a "ball" or "globe" (o); a camp all around; the Lord is said to do that which the enemy should do, because it was by his will, and according to his order, and which he would succeed and prosper, and therefore the prophecy of it is the more terrible; and it might be concluded that it would certainly be fulfilled, as it was; see Luke 19:43,
and will lay siege against thee with a mount: raised up for soldiers to get up upon, and cast their arrows into the city from, and scale the walls; Kimchi and Ben Melech interpret it a wooden tower. This cannot be understood of Sennacherib's siege, for he was not suffered to raise a bank against the city, nor shoot an arrow into it, Isaiah 37:33 but well agrees with the siege of Jerusalem by the Romans, as related by Josephus (p):
and I will raise forts against thee; from whence to batter the city; the Romans had their battering rams.
(o) "quasi pila", Piscator; "instar globi", Gataker. (p) Joseph. de Bello Jude. l. 5. c. 7. sect. 1. & c. 12. sect. 1, 2.

I--Jehovah, acting through the Assyrian, &c., His instruments (Isaiah 10:5).
mount--an artificial mound formed to out-top high walls (Isaiah 37:33); else a station, namely, of warriors, for the siege.
round about--not fully realized under Sennacherib, but in the Roman siege (Luke 19:43; Luke 21:20).
forts--siege-towers (Deuteronomy 20:20).