📚 Yuanshen Haikua — a Qing-dynasty endgame manual
This is one of the rare positions where the classical book and the computer argue openly. Red to move, both armies still large — Red has two chariots, two cannons, a knight; Black keeps both advisors and elephants, two knights, two chariots. The classical manual Uyên Thâm Hải Khoát (game 260) concludes: Red wins. But Fairy-Stockfish disagrees outright: by the machine's reckoning, Black checkmates Red in just 7 moves. One side has misread the whole position. The name comes from the Warring-States 'horizontal alliance' stratagem: Zhang Yi promised Chu 600 li of land to break its alliance with Qi, then delivered six. That diplomatic swindle — and the price Chu paid — is told below. A printed verdict that may itself be a '600-li promise': do you trust the old book or the machine — and can you work out which one is right?
⚖ Disputed — The Fairy-Stockfish engine (NNUE) overturns the classical book's result: Black checkmates Red in 7 moves — the main line was checked move by move, every move legal. Date checked: 2026-11-03.
Promised 600 li, delivered 6: the diplomatic swindle that cost a state its land
Zhang Yi, chancellor of Qin, went to Chu and promised King Huai: break off relations with Qi, and Qin will give Chu 600 li of land. The king, greedy for land, broke with Qi and even sent a man to insult the king of Qi. But when Chu's envoy came to collect the land, Zhang Yi produced a very…
Stories around this position — storytelling, not part of the engine-verified content.
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