Hezekiah Rebels Against Assyria (2 Kings 18:7-8; 1 Chronicles 4:24-43; 2 Kings 20:20) April 30
It has already been mentioned that there was a "spirit of general rebellion following Sargon's death in 705 [B.C.]" (Merrill, Kingdom of Priests, p. 416). In 703 Merodach-Baladan was back on the throne of Babylon for a short period. Yet the new Assyrian emperor, Sennacherib, "prevailed, took the city of Babylon, and reasserted Assyrian authority" (p. 414). "Meanwhile, with Egyptian encouragement Hezekiah also rebelled" (p. 414). We read of this rebellion in 2 Kings 18:7.
The Macmillan Bible Atlas relates more details of what happened: "The time of greatest trial for Judah [Sennacherib's invasion of 701 B.C.] was soon to come. The death of Sargon was a sign for new uprisings throughout the kingdom and Hezekiah king of Judah stood at the head of the conspirators in Palestine. Among the cities of Philistia, Ashkelon raised the banner of revolt [against Assyria] and the people of Ekron joined the conspiracy, after deposing their king, Padi, and sending him in chains to Hezekiah...
"Hezekiah understood the extent of the danger which he incurred and began to prepare extensively for the coming conflict. His most famous work was the hewing of the Siloam water conduit in Jerusalem, which carried water from the spring of Gihon into the city" (p. 98). We read of this already in the highlights for Isaiah 22.
"He also strengthened the fortifications of Jerusalem (Is. 22:8-11) and fortified and provisioned the central cities of Judah (1 Chron. 4:38-41). The borders of the kingdom were expanded at the expense of the kingdoms which had refused to join the conspiracy, mainly in the direction of Gaza and Edom (2 Kings 18:8; 1 Chron. 4:42-43)" (p. 98). Thus, Hezekiah's subjugation of the Philistines in 2 Kings 18:8 refers not to all the Philistines but to those that would not join his rebellion as Ashkelon and Ekron did.
The concluding phrase "to this day" offers some interesting insight into how the Bible was written, for it clearly refers to whatever point it time it was when the author of this section penned this notation. See How to Understand the Bible for more information on how God used many authors over many years to compile what we now have as the Bible.