Why do cannons get weaker in the endgame?
These answers restate the rules implemented by our open-source engine, which follows the WXF laws and is regression-tested against the official 110-diagram repetition casebook. Where an answer refers to a specific position, that position lives on the linked reference page, where the build verifies it against the engine before publishing.
Direct answer
Because every trade removes a potential screen. A cannon can only capture across exactly one piece, so the emptier the board, the less it can do — until, against a bare general in an empty palace, it cannot even give check. Every other piece gets simpler as material comes off; the cannon gets harder.
Trade accordingly
If the game is heading for an endgame, trade your cannon for their horse rather than the reverse. The horse is strengthening at the same rate the cannon is weakening, so the exchange is better than the nominal values (4.5 against 4) suggest.
Keeping a cannon alive
- Keep an advisor. It is a screen you control, and cannon-plus-advisor beats a bare general.
- Use their pieces. A defender's elephants sitting at home are screens you did not have to supply.
- Attack along the general's file, because the palace is where the defender's remaining pieces are — and therefore where screens survive longest.
Related questions
Is a horse always better late?
In most open endgames, yes. If the defender still has both advisors, a cannon keeps more of its value than the rule of thumb suggests.
Should I trade cannons early then?
Not early — a cannon is at its best when the board is full. Trade it while it is still worth something.
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