2 Kings 18:13

Sennacherib, king of Assyria, invades Judah. Hezekiah submits, and pays a large tribute (2 Chronicles 32:1; Isaiah 36:1)

13. Sennacherib king of Assyria Sennacherib was the son of Sargon, but as it seems not the eldest, and only became heir to the throne in the year before his father's death. He is said to have begun his reign b.c. 705 and to have been murdered in 681. The operations against Hezekiah seem to have been only part of a larger campaign, which appears to have been directed against those states which were in alliance with Egypt. For the Assyrian troops had gone beyond Jerusalem, and were at Lachish when Hezekiah sent in his submission. According to the inscriptions Sennacherib had overrun Phœnicia and advanced along the coast to attack the cities of the Philistines. We can see from 2 Kings 19:8-9 that the Egyptian power was advancing from the south, and eventually caused more pressure to be put on Jerusalem by the Assyrians that they might reduce it if possible, before aid arrived from Egypt. For we may be sure that Hezekiah in his attempt to shake himself free from Assyria had, like his neighbours, sought the friendship of the Egyptians.

all the fenced cities of Judah These were subjugated first, that there might be no chance of help from them if it became necessary to assault the capital. With some cities of the Philistines already in his hands, it would be easy for Sennacherib to overrun Judæa and capture the less fortified places.