By this news Sennacherim was led to return in order to defend his own territories, and he gave up the war, at the same time murmuring and crying out that victory was snatched from him the victor. He also sent letters to Ezekias, declaring, with many insulting words, that he, after settling his own affairs, would speedily return for the destruction of Judæa. But Ezekias, in no wise disturbed by these threats, is said to have prayed to God that he would not allow the so great insolence of this man to pass unavenged.
Accordingly, in the same night, an angel attacking the camp of the Assyrians, caused the death of many thousand men. The king in terror fled to the town of Nineveh, and being there slain by his sons, met with an end worthy of himself. At the same time, Ezekias, sick in body, lay suffering from disease. And when Isaiah had announced to him in the words of the Lord that the end of his life was at hand, the king is related to have wept; and thus he got fifteen years added to his life.
These coming to an end, he died in the twenty-ninth year of his reign, and left the kingdom to his son Manasse. He, degenerating much from his father, forsook God, and took to the practice of impious worship; and being, as a punishment for this, delivered into the power of the Assyrians, he was by his sufferings constrained to acknowledge his error, and exhorted the people that, forsaking their idols, they should worship God. He accomplished nothing worthy of special mention, but reigned for fifty-five years. Then Amos his son obtained the kingdom, but possessed it only two years. He was the heir of his father's impiety, and showed himself regardless of God: being entrapped by some stratagems of his friends, he perished.
Source: Sacred History (New Advent)