We know of the siege of Jerusalem in 701BC not only from the Bible but also from Assyrian sources. Historians speculate that two factors contributed to the successful (from Jerusalem’s perspective) outcome. First, the Jewish king paid a tribute to the Assyrians so they could chalk it up as a “win.” Second, some kind of plague infected the Assyrian army during the siege so they cut their losses and went home. The plague was probably cholera since, in preparation for the invasion, the Jewish king had diverted all the water into the city so the invaders would not have fresh water. The prophet ascribes the lifting of the siege to divine intervention but part of the divine help was human wits playing a role.