And he shall cut down the thickets of the forest - The army of the Assyrians, described here as a thick, dense forest; compare Isaiah 10:18-19.
With iron - As a forest is cut down with an axe, so the prophet uses this phrase here, to keep up and carry out the figure. The army was destroyed with the pestilence 2 Kings 19:35; but it fell as certainly as a forest falls before the axe.
And Lebanon - Lebanon is here evidently descriptive of the army of the Assyrian, retaining the idea of a beautiful and magnificent forest. Thus, in Ezekiel 31:3, it is said, ‘the king of the Assyrians was a cedar of Lebanon with fair branches.’ Lebanon is usually applied to the Jews as descriptive of them (Jeremiah 22:6, Jeremiah 22:23; Zechariah 10:10; Zechariah 11: l), but it is evidently applied here to the Assyrian army; and the sense is, that that army should be soon and certainly destroyed, and that, therefore, the inhabitants of Jerusalem had no cause of alarm; see the notes at Isaiah 37.