John Gill Commentary 2 Kings 18:10

"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." — 2 Kings 18:10 (ASV)

And at the end of three years they took it
That is, at the first end of them, at the beginning, in which sense the phrase is taken in (Deuteronomy 15:1) (Jeremiah 34:14) , even in the sixth year of Hezekiah, that is, the ninth year of Hoshea king of Israel, Samaria was taken: see (2 Kings 17:6) .