Charles Ellicott Commentary 2 Kings 18:9-12

"And it came to pass in the fourth year of king Hezekiah, which was the seventh year of Hoshea son of Elah king of Israel, that Shalmaneser king of Assyria came up against Samaria, and besieged it. And at the end of three years they took it: in the sixth year of Hezekiah, which was the ninth year of Hoshea king of Israel, Samaria was taken. And the king of Assyria carried Israel away unto Assyria, and put them in Halah, and on the Habor, the river of Gozan, and in the cities of the Medes, because they obeyed not the voice of Jehovah their God, but transgressed his covenant, even all that Moses the servant of Jehovah commanded, and would not hear it, nor do it." — 2 Kings 18:9-12 (ASV)

The account of the captivity of northern Israel is repeated here, because the editor faithfully reproduces what he found in the abstract of the Judean history of the kings. (Compare to 2 Kings 17:3–6, and the Notes.) We may also see a contrast between the utter overthrow of the stronger kingdom and the deliverance of its smaller and weaker neighbor, because Hezekiah trusted in Jehovah (2 Kings 18:5).