And I will camp against thee round about, and will lay siege against thee with a mount, and I will raise forts against thee.
I - Yahweh, acting through the Assyrian, etc., my instruments (Isaiah 10:5).
Will camp against thee round about. Since Sennacherib did not encompass the city "round about" (literally, like a round ball or circle: kaduwr (H1754)), the ulterior reference is to the Babylonian and Roman sieges. (Luke 19:43; Luke 21:20).
A mount - an artificial mound formed to out-top high walls (Isaiah 37:33). Else a station-namely, of warriors, for the siege.
Forts - siege towers (Deuteronomy 20:20).