In 18:9—19:37 we have an account of the invasion of the Assyrians.
In the fourth year of Hezekiah, the seventh year of Hoshea king of Israel, Shalmaneser king of Assyria came up against Samaria and besieged it (v. 9). At the end of three years, in the sixth year of Hezekiah and the ninth year of Hoshea, Shalmaneser took Samaria and carried Israel away captive (vv. 10-11; 17:3-6). This took place because Israel would not listen to the voice of Jehovah nor do it (18:12).
In 18:13—19:37 we read of the attacking and challenging of Sennacherib king of Assyria with insult and blasphemy.
Sennacherib went up against all the fortified cities of Judah and took them (18:13).
Hezekiah king of Judah subjected himself to Sennacherib. As Sennacherib imposed upon him, Hezekiah paid him quite a great amount of silver and gold from the temple of Jehovah and the treasuries of the king's house (vv. 14-16).
Sennacherib challenged Hezekiah with insult and blasphemy through Rab-shakeh with his army (vv. 17-37; 19:8-13).
Hezekiah appealed to Isaiah the prophet. Isaiah told him that Jehovah would cause the king of Assyria to return to his land and to fall by the sword in his own land (19:1-7).
Hezekiah went up to the temple of Jehovah, spread the challenging letter before Jehovah, and prayed to Jehovah, asking for salvation (vv. 14-19).
Jehovah answered Hezekiah through Isaiah the prophet, saying that He would turn the king of Assyria back by hooking him in his nose and bridling him in his lips and that Jerusalem would be preserved for His own sake and for the sake of David His servant (vv. 20-34).
In that night an angel of Jehovah went out and slaughtered the Assyrians' camp of 185,000, and Sennacherib king of Assyria departed and went back to dwell in Nineveh. Eventually he was killed, probably by his sons, and Esarhaddon his son reigned in his place (vv. 35-37).