Hezekiah
Under the influence of Isaiah, King Hezekiah (727-698 B.C.E.) purified the Temple and strengthened the walls of Jerusalem. In an effort to ensure Jerusalem's ability to withstand a siege, Hezekiah also dug a water tunnel, 533 meters long, from the spring of Gihon into a reservoir inside the city walls at the pool of Siloam.

Some believe that Hezekiah's purification of the Temple and contribution to the safety of Jerusalem is the reason that God protected the city when Assyrians besieged it:

That night an angle of the Lord went out and struck down one hundred and eighty-five thousand in the Assyrian camp, and the following morning they were all dead corpses. So King Sennacherib of Assyria broke camp and retreated, and stayed in Nineveh. (2 Kings 19:35-36)