Lay waste defended cities into ruinous heaps "Lay waste warlike nations; strong fenced cities" - נצים גלים gallim nitstsim . It is not easy to give a satisfactory account of these two words, which have greatly embarrassed all the interpreters, ancient and modern. For גלים gallim I read גוים goyim, as the Septuagint do in this place, εθνη . The word נצים netsim the Vulgate renders in this place compugnantium; in the parallel place, 2 Kings 19:25, pugnantium; and the Septuagint μαχιμων, fighting, warlike. This rendering is as well authorized as any other that I know of; and, with the reading of the Septuagint, perfectly clears up the construction. See the margin on all the preceding verses.
Hast thou not heard - This is evidently the language of God addressed to Sennacherib. It is designed to state to him that he was under his control; that this was the reason Isaiah 37:27 why the inhabitants of the nations had been unable to resist him; that he was entirely in his hands Isaiah 37:28; and that lie would control him as he pleased Isaiah 37:29.
Long ago how I have done it - You boast that all this is by your own counsel and power. Yet I have done it; that is, I have purposed, planned, arranged it long ago (compare Isaiah 22:11).
That thou shouldest be to lay waste - I have raised you up for this purpose, and you have been entirely under my control (see the note at Isaiah 10:5).