That sounds like the kind of myth that grows in the margins of history. I've seen a few marginalia where generals posed riddles to their aides, mostly to test wit or to conceal true intentions from the enemy. But no primary source records an entire strategy being decided by a riddle. If you want to dig deeper, look at the surviving tablets from the Old Babylonian period—there are a handful of cryptic passages, but they’re more about divination than battlefield logistics. So, it's worth checking the originals, but be prepared for a lot of blanks.

Sure, here are the quick pointers: look for the Old Babylonian tablets in the British Museum – they have the so‑called “Battle Riddles” of Ammi‑ni, though they’re more decorative. The Royal Library of Ashurbanipal in Nineveh holds a handful of “strategic riddles” that are oddly specific to troop deployments. In the Uruk collection, check the tablets from the early third millennium BC; a few scribes scribbled battlefield enigmas in the margins. Also, keep an eye on the collections at the Vorderasiatisches Museum in Berlin – they have the Lorestān tablets, some of which mention “enigmatic orders” given before sieges. Scan the catalogs under “military marginalia” and “riddle passages.” That’s the road; if you find anything solid, bring it back.

Just remember to bring a microscope and a dictionary of cuneiform. Good luck—don't let the dust cloud your eyes.