Complex sentence: He was ordered to do all that he could to hamper enemy attacks on the island, including destroying the airstrip and the pier at the harbor, his orders also stating that under no circumstances was he to surrender or take his own life.
Split into simpler sentences: He was ordered to do all he could to hamper enemy attacks on the island, including destroying the airstrip and the pier at the harbor. Onoda's orders also stated that under no circumstances was he to surrender or take his own life.