Charles Ellicott Commentary 2 Kings 17:5

"Then the king of Assyria came up throughout all the land, and went up to Samaria, and besieged it three years." — 2 Kings 17:5 (ASV)

Then (and) the king of Assyria came up ... and besieged it three years. —Sargon states that he took Samaria (Samer ί na) in his first year. Shalmaneser therefore had besieged the city some two years before his death.

The brief narrative before us does not discriminate between the respective shares of the two Assyrian sovereigns in the overthrow of the kingdom of Israel, but it is noticeable that it does not say that Shalmaneser “besieged Samaria three years,” and “took Samaria.” (Compare to 2 Kings 18:11; 2 Kings 18:11.)