Complex sentence: All of the vanquished leaders save one were sent to Nineveh, only Necho I the native Egyptian Prince of Sais, convinced the Assyrians of his loyalty and was sent back to become the Assyrian puppet Pharaoh of Egypt.
Split into simpler sentences: All of the vanquished leaders save one were sent to Nineveh. Only Necho I, the native Egyptian Prince of Sais, convinced the Assyrians of his loyalty and was sent back to become the Assyrian puppet Pharaoh of Egypt.