John Calvin Commentary Deuteronomy 28:52

"And they shall besiege thee in all thy gates, until thy high and fortified walls come down, wherein thou trustedst, throughout all thy land; and they shall besiege thee in all thy gates throughout all thy land, which Jehovah thy God hath given thee." — Deuteronomy 28:52 (ASV)

And he shall besiege thee in thy gates. He overthrows every ground of false confidence. The number of their towns inspired them with courage, because they never would have supposed that their enemies would undergo so much fatigue as not to cease from fighting until they were all taken. He therefore includes all their towns; trusting in their large number, they despised hostile aggression.

He adds, that they trust in vain in their high and fortified walls, which will be either overthrown by military engines, or shall voluntarily surrender from the length of their siege. For the passage may be explained in both ways: either that the enemies shall overthrow and lay prostrate all their fortresses, or that by their perseverance they shall pass over the walls, however high. It seems to me that the length of the siege as well as their valiant fighting is indicated.

The repetition which follows magnifies the evil, namely, that they shall be thus sorely pressed in their own land given them by God; for the very associations of the place only increased the indignity.