A letter scratched into a clay tablet reveals a desperate plea for reinforcements that came just too late. Alone, petrified and facing almost certain death, the ancient Assyrian leader Mannu-ki-Libbali scrawled a call for help to his commander, but his cry for extra troops came too late.

Soon after it was sent, the ancient city of Tushan was overrun by Babylonian invaders, its temples and palaces pillaged, then torn down or set aflame.
The letter, scratched into a clay tablet in 630BC, may never have reached its intended recipient. But more than …