Tiglath-Pileser III and other Assyrian kings had assumed Babylonian sovereignty except the periods when Merodach-baladan II ruled. But when the mighty Assyrian monarch Sennacherib (704-681 BC) gained power and built his empire, he placed puppet kings throughout his empire to assure non-resistance. This system worked well for Sennacherib's empire, that is until his own son was captured by the Babylonians and handed over to the Elamites. Sennacherib was so outraged that he not only led fierce campaigns against the Elamites, but he conquered and then destroyed Babylon in 689 BC.