Sennacherib was the son of Sargon II

Sargon II

Sargon II was an Assyrian king. Sargon II became co-regent with Shalmaneser V in 722 BC, and became the sole ruler of the kingdom of Assyria in 722 BC after the death of Shalmaneser V. It is not clear whether he was the son of Tiglath-Pileser III or a usurper unrelated to the royal family...

, whom he succeeded on the throne of Assyria

Assyria

Assyria was a Semitic Akkadian kingdom, extant as a nation state from the mid–23rd century BC to 608 BC centred on the Upper Tigris river, in northern Mesopotamia , that came to rule regional empires a number of times through history. It was named for its original capital, the ancient city of Assur...

 (705 – 681 BC).
As the crown prince

Crown Prince

A crown prince or crown princess is the heir or heiress apparent to the throne in a royal or imperial monarchy. The wife of a crown prince is also titled crown princess....

, Sennacherib was placed in charge of the Assyrian Empire while his father, Sargon II

Sargon II

Sargon II was an Assyrian king. Sargon II became co-regent with Shalmaneser V in 722 BC, and became the sole ruler of the kingdom of Assyria in 722 BC after the death of Shalmaneser V. It is not clear whether he was the son of Tiglath-Pileser III or a usurper unrelated to the royal family...

, was on campaign. Unlike his predecessors, Sennacherib's reign was not largely marked by military campaigns, but mainly by architectural renovations, constructions, and expansions. After the violent death of his father, Sennacherib encountered numerous problems in establishing his power and faced threats to his domain.