Why is a horse better than a cannon 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 emptiness helps one and hurts the other. Fewer pieces means fewer legs blocked for the horse, so it moves freely. It also means fewer screens for the cannon, which cannot capture without exactly one — so the cannon fades as the horse improves, and by the endgame they have swapped places.
The practical rule
If the game is heading for an endgame, trade your cannon for their horse. The nominal values (4.5 against 4) say you are losing half a point; the direction of travel says otherwise, and the direction of travel is what matters.
When it does not apply
If the defender still has both advisors, the palace remains full of screens and the cannon keeps more of its value. And a horse that needs four moves to reach the action is worth less than its number regardless of how empty the board is — count the moves.
Related questions
Can a lone horse mate?
No. It needs a soldier, an advisor or another piece.
What stops a horse in the endgame?
Blocking its leg — and in bare endgames the defender's own general is very often the piece doing it.
.