Thirty-five centuries ago, a desperate young Egyptian queen sent a pleading letter to a Hittite king, Shubbiluliuma, an enemy of Egypt: 'My husband has died. I have no sons. There is no heir to the throne of Egypt. Never shall I pick a servant of mine to make him my husband. Thou have many sons, they say. If thou send me one of thy sons, he shall become my husband and King of Egypt. I am afraid.' Shubbiluliuma was sceptical and suspicious. Egypt and...