yù bàng xiāng zhēng

Literal: The Snipe (鷸, yù) and the Clam (蚌, bàng) fight each other(相爭, xiāng zhēng)

Actual: The third party in a conflict always wins

King Hui led the Zhao kingdom during the Warring States period. During one of his daily stand-up meetings, he declared: “We have a solid chance at acquiring the Yan kingdom - our soldiers itch for war. Any objections?”

Su Dai, one of his trusted advisors, quietly groaned. Wars were expensive, not to mention that the neighboring Qing empire was also expanding at a dangerous pace. Su Dai approached the King and started telling a story.

“I saw something odd the other day - a giant, sun-bathing Clam with its shell open. Along flew a Snipe, who quickly spotted the sand-bathing Clam. ‘Aha! Gourmet seafood for lunch!’ The Snipe swooped down and jabbed its beak into the juicy Clam, which quickly slammed its shell shut on the Snipe’s beak.

‘Ack!’ Yelled the Snipe. ‘You won’t get away with this! I’ll wait until tomorrow, and without any rain you’ll soon dry out!’ The Clam chuckled. ‘Oi! I’m in no bloody hurry either - by tomorrow you’ll die of thirst, ya wanker!’” (Su Dai coughed - his British accent needed some work) “‘Well I suppose we’ll see who wins then,’ said the Snipe.

Some time went by, and along came a fisherman tired from a day’s work. ‘Ah ha! What a prize! Seafood AND roasted bird for me!’ The fisherman promptly bagged the clam and bird, who were still too angry to release each other and escape their doom.”

King Hui held back his various questions about the story (“Why do clams sound British?”) and nodded his head. “I see your point - it would be foolish to attack now. Dismissed!” Su Dai released a sigh of relief.

TL;DR: An advisor convinces the king not to wage a costly war of attrition. Dragging people down with you may be satisfying, but not as much as third-party profiteering - CIA-in-the-middle-east-style.