Battle of Nihriya

Hattusili's son, Tudhaliya IV, was the last strong Hittite king able to keep the Assyrians out of the Hittite heartland to some degree at least, though he too lost much territory to them, and was heavily defeated by Tukulti-Ninurta I of Assyria in the Battle of Nihriya. He even temporarily annexed the Greek island of Cyprus, before that too fell to Assyria.