Short answer is yes, Sennacherib goes back to Assyria, but no, the Assyrian army probably did not get wiped out by a plague.

Along with 2 Kings 18-19, we have the Assyrian account of the seige of Jerusalem in 701 BCE. This is the famous relevant passage about the seige as described by Sennacherib (emphasis mine):

“As for him (Hezekiah), I confined him inside the city Jerusalem, his royal city, like a bird in a cage. I set up blockades against him and made him dread exiting his city gate. I detached from his land the cities of his that I had plundered and I gave (them) to Mitinti, the king of the city Ashdod, and Padî, the king of the city Ekron, (and) Ṣilli-Bēl, the king of the land Gaza, (and thereby) made his land smaller. To the former tribute, their annual giving, I added the payment (of) gifts (in recognition) of my overlordship and imposed (it) upon them. As for him, Hezekiah, fear of my lordly brilliance overwhelmed him and, after my (departure), he had the auxiliary forces (and) his elite troops whom he had brought inside to strengthen the city Jerusalem, his royal city, thereby gaining reinforcements, (along with) 30 talents of gold, 800 talents of silver, choice antimony, large blocks of ..., ivory beds, armchairs of ivory, elephant hide(s), elephant ivory, ebony, boxwood, garments with multi-colored trim, linen garments, blue-purple wool, red-purple wool, utensils of bronze, iron, copper, tin, (and) iron, chariots, shields, lances, armor, iron belt-daggers, bows and uṣṣu-arrows, equipment, (and) implements of war, (all of) which were without number, together with his daughters, his palace women, male singers, (and) female singers brought into Nineveh, my capital city, and he sent a mounted messenger of his to me to deliver (this) payment and to do obeisance.” [1]

The context here is Sennacherib’s father Sargon II had died in battle in 705 BCE, and the vassals of the Assyrians try to take advantage of the messy succession crisis by withholding tribute and throwing off Assyrian rule.

Hezekiah of Judah is one of the leaders of a revolt that stretches the Levant. Sennacherib responds with a show of force, and the mere presence of his army makes most of the rebels fold. Hezekiah is one of those who resist, and, militarily, it goes badly for him— most notably the city of Lachish is beseiged and destroyed. As the Bible goes into in detail, Sennacherib eventually surrounds Jerusalem but does not take the city, only sending his generals to deliver an ultimatum to surrender. And like the Biblical account says, Hezekiah is forced to pay tribute (The lists are close in the Assyrian and Biblical accounts.). He also hands over a neighboring pro-Assyrian king who was held hostage in Jerusalem.

Sennacherib elides the fact that he doesn’t conquer Jerusalem, but both accounts agree that he succeeds in forcing Hezekiah to resume paying tribute and recognizing Assyrian suzerainty. The Bible and Hezekiah also spin it as a win, and Hezekiah stays in power. The Bible adds more drama with an additional threatening letter from the Assyrian generals (likely made up) and ends the story with Sennacherib’s murder and coup as punishment for the seige. But, in reality, after Sennacherib leaves, he reigns for another 20 years.

As for the plague that strikes the Assyrian camp, there is no historical evidence. It’s certainly possible. But, the best explanation is Sennacherib, having quelled his Levantine rebels and forced them to resume tribute, had accomplished his goals and didn’t need to conquer Jerusalem. And, at the same time, there was trouble brewing in Babylonia with two rebel leaders revolting against Assyrian rule. The intractable Babylonian problem would take up the rest of Sennacherib’s reign and persist until the end of the Neo-Assyrian period. Sennacherib’s army was most needed there in his imperial core.[2]

Sources

[1] RINAP 3/1 4 http://oracc.museum.upenn.edu/rinap/rinap3/corpus

[2] Frahm, E. “Assyria and the South: Babylonia,” in A Companion to Assyria. (2017)