After the death of Tiglath-pileser III in 727, rebellions broke out in the Assyrian empire. During the period of Hezekiah's reign, Judah made several attempts to rebel against Assyrian domination, including religious reforms - returning to the worship of Yahweh, purging the land of idolatry, and withholding tribute. Hezekiah looked for allies, including Merodach-Baladan of Babylon (Is 39) and Egypt.
Hoshea, the last king of Samaria, was a vassal of Assyria. He rebelled by forming an alliance with Egypt, which was no help to him. Shalmaneser V of Assyria invaded and besieged Samaria for three years, which fell in 722 BC, as predicted by Amos and Hosea fifty years earlier. During the siege of Samaria, Shalmaneser died and was succeeded by Sargon II. For his first seven or eight years, Sargon had troubles from Merodach-baladan of Babylon and in Urartu in the north, so he left Judah in peace.
Ethiopia (southern Egypt) gained strength and gained control over the whole of Egypt. Egypt emerged as the champion of the nations subjugated by Assyria, “Egypt their boast, Ethiopia their hope” (Is 20:5). Hezekiah reversed the policy of his father, Ahaz, and became pro-Egypt, rather than pro-Assyrian.
Isaiah warned against trusting in Egypt (Is 18:1 & ch 29-31), as they were not really strong and could not offer real help (31:1-3). Isaiah removed his sackcloth and shoes as a sign that Egypt and Ethiopia would become captives of Assyria (Is 20).
Ashdod (Philistia) lost her battle against Assyria, being defeated in 715 to 713. This was predicted in Is 14:28-31. Their leader fled to Egypt for asylum, but was handed back to Assyria. Judah did not participate in this battle.
Babylon rebelled against Assyrian rule in 705 BC, and tried to get Judah to join them in their effort to throw off the Assyrian yoke. Merodach-baladan of Babylon visited Hezekiah to congratulate him on his recent recovery from sickness, but his real motive was to strengthen the alliance with Hezekiah against their joint oppressor, Assyria (Is 38:6, Is 39). Hezekiah coordinated the resistance movement, forming a coalition with Philistia, Edom and Moab, using Egypt's strength (Is 30:1-7, 31:1-3). Everyone, except Isaiah, rejoiced over the alliance with Egypt. Hezekiah had turned to Egypt, just as Ahaz had trusted in Assyria (Is 30).
Possibly this was the time when Isaiah told Hezekiah to get his house in order because he was about to die (Is 36:1). He had fifteen years added to his life, making a total reign of twenty-nine years. God made a promise to Hezekiah that he would deliver him and the city of Jerusalem out of the hand of the King of Assyria (Is 38:6-7).
In 703 BC, Sennacherib dealt with Merodach-baladan, the rebellious king of Babylon. He then defeated the combined forces of Egypt and Ekron, as Egypt had come to help Ekron. Instead of marching into Egypt, Sennacherib attacked Judah to bring his rebellious vassal Hezekiah back under Assyrian control, taking forty-six walled cities, including Lachish and 200,000 people captive (2 Kg 18:13). During the siege of Lachish (2 Kg 18:14-16), Sennacherib received a message that Hezekiah had repented for his rebellion and that he had asked for peace at any cost (2 Kg 18:14). Sennacherib sent messages to Hezekiah, who paid tribute, three hundred talents of silver and thirty talents of gold, even stripping the gold from the door of the temple, but this was not enough.
Jerusalem was besieged by Sennacherib's Rabshakeh (the second in command of the army), who mocked the God of Hezekiah (2 Kg 18:35, 19:10, Is 36:4). Sennacherib besieged Jerusalem, and said that "he had trapped Hezekiah in Jerusalem like a bird in a cage", and demanded his surrender. In response, Isaiah told Hezekiah to trust God. Through Isaiah, God promised deliverance. Hezekiah trusted God by refusing to give in to the Assyrian armies and God delivered Judah from the hand of Assyria. After over fiftyyears of ministry, someone finally believed Isaiah's word to trust God. God proved faithful to Hezekiah and gave miraculous deliverance.
There was a rumour, predicted by Isaiah, that Tirhakah of Ethiopia was coming against Assyria (2 Kg 19:9, Is 37:7), the Assyrians temporarily withdrew from Jerusalem. When they returned, God's angel killed 185,000 of their troops (2 Kg 19:35). Herodotus wrote that the Assyrian army was killed by a plague of mice (possibly bubonic plague carried by rats). God supernaturally destroyed the Assyrian army, which led to the decline of Assyria as a world power (2 Kg 18-19). Sennacherib did not attempt to conquer Jerusalem again, Judah was left in peace. Sennacherib was murdered by his sons, in 681 BC (37:38) and his son Esarhaddon succeeded him.
From the Annals of Sennacherib on the Taylor Prism in the British Museum
"As to Hezekiah the Jew, he did not submit to my yoke, I laid siege to forty-six of his strong cities, walled forts and to the countless small villages in their vicinity, and conquered them by means of well stamped earth ramps, and battering rams brought thus near the attack by foot soldiers. I drove out 200,150 people, young and old, male and female horses, camels, mules, donkeys, big and small cattle beyond counting and considered them booty. I had Hezekiah trapped in Jerusalem like a bird in a cage. I took tribute from Hezekiah, thirty talents of gold & three hundred talents of silver."
The Book of Isaiah shows a great contrast between Ahaz and Hezekiah. Ahaz refused to trust God, preferring to trust Assyria with the consequence of losing his nation’s freedom; but Hezekiah, against all odds, trusted God and was delivered.
This great deliverance is predicted a number of times in the prophets: Isaiah predicted that the flood of Assyrian invasion of Judah will reach even to the neck (Is 8:7-8), implying that all Judah will be conquered except for Jerusalem. He also predicted the route of the invading Assyrian army, that they will halt at Nob and shake his fist at Jerusalem (10:28-32). He predicted the siege of Jerusalem and sudden destruction of enemy (29:1-8). Micah also named some of the forty-six cities taken by Assyria (Micah 1).