Following the death of King Ahaz, his son Hezekiah ascended the throne in Jerusalem. The new monarch introduced comprehensive religious reform and introduced substantial policy changes.
Hezekiah renewed the full-scale worship of the Israelite God following a lengthy period in which idol-worship had taken root in the city: "He abolished the shrines and smashed the pillars and cut down the sacred post. He also broke into pieces the bronze serpent which Moses had made, for until that time the Israelites had been offering sacrifices to it "(2 Kings 18:4). At the same time he renewed the tradition of the Passover pilgrimage in its full scope, and for the first time since the kingdom had split, under Rehoboam son of Solomon, the remnants of the tribes of Israel, those who had not gone into the Assyrian exile, were invited to take part in the most sumptuous festival which had been seen for many generations. Hezekiah took advantage of the festival to consolidate his religious reforms and to return the people to the worship of God: "A great crowd assembled at Jerusalem to keep the Feast of Unleavened Bread in the second month, a very great congregation. They set to and removed the altars that were in Jerusalem, and they removed all the incense stands and threw them into Wadi Kidron...There was great rejoicing in Jerusalem, for since the time of King Solomon son of David of Israel nothing like it had happened in Jerusalem" (2 Chronicles 30:13, 26).
At the same time Hezekiah revised the political approach of his father Ahaz, appealing to Egypt to halt the Assyrian expansion. His pragmatic approach was scornfully criticized by the prophet Isaiah, who was very active and highly influential in Jerusalem during this period: "Ha! Those who go down to Egypt for help and rely upon horses! They have put their trust in abundance of chariots, in vast numbers of riders, and they have not turned to the Holy One of Israel, they have not sought the Lord" (Isaiah 31:1).
The prophet's theopolitical approach claimed that the Assyrian conquests were no more than a sign and an omen to the people to resume the worship of God with a full heart, and that any attempt to rely on "earthly" military help was doomed to failure. For the same reason he rejected the efforts to form an alliance with Babylon (2 Kings 18). Hezekiah also made concrete preparations for the Assyrian siege that Sennecharib finally laid on Jerusalem in 701 BCE, some 20 years after his predecessor, Tiglath-pileser, had ravaged the northern Kingdom of Israel. In an impressive engineering feat a tunnel 533 meters long was dug in order to provide underground access to the waters of the Gihon Spring, which lay outside the city: "When Hezekiah saw that Sennacherib had come, intent on making war against Jerusalem, he consulted with his officers and warriors about stopping the flow of the springs outside the city, and they supported him. A large force was assembled to stop up all the springs and the wadi that flowed through the land, for otherwise, they thought, the King of Assyria would come and find water in abundance "(2 Chronicles 32:2-4).
Adventurous visitors to Jerusalem can still explore this 2700-year-old technological wonder. In the Siloam Tunnel, which was dug from two different directions in order to speed up the work in the face of the advancing enemy, we find the "Siloam inscription," which commemorates the meeting of the two teams. At the same time, a wall was built around the Siloam Pool, into which the spring waters were channeled; the wall continued westward and surrounded the city, which at this time expanded to the slopes of Mount Zion. An impressive vestige of this structure, the building of which is described in Isaiah 22:11, is the broad wall in the Jewish Quarter of the Old City of Jerusalem. Miraculously, the city was spared the siege, although a realistic explanation was also offered for this development.