In 664 BC, the Assyrians laid the final blow, sacking Thebes and Memphis. The same year, Taharqa died. The new Kushite king, Tantamani (664–653 BC), killed Necho I that same year when he tried to invade Lower Egypt. However, Tantamani was unable to defeat the Assyrians, who backed Necho’s son, Psamtik I. Tantamani eventually abandoned his attempt to conquer Lower Egypt and retreated to Napata. However, his authority over Upper Egypt was acknowledged until the 8th regnal year of his reign at Thebes (or 656 BC), when Psamtik I dispatched a naval fleet to Upper Egypt and succeeded in placing all of Egypt under his control.