What is 馬後炮 (horse behind cannon)?
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
馬後炮 — literally "cannon behind the horse" — is the most recognisable mate in xiangqi. The horse sits in front of the enemy general and the cannon behind it on the same line, using the horse as its screen. The horse covers the two sideways escape points, and the general has nowhere to go.
Why the general cannot escape
- Sideways — both points are covered by the horse.
- Toward the cannon — still on the line, still checked.
- Capture the horse — out of reach; it is two points away, not adjacent.
Two pieces, no support needed. That is why it turns up at every level of play.
Building it
The horse goes first, almost always. It takes three or four moves to reach the point in front of the palace but is very hard to dislodge once there. The cannon can arrive in one move, which is why the mate often seems to appear out of nowhere.
The name is also an everyday Chinese idiom meaning advice that arrives too late — a shot fired after the moment has passed.
Related questions
Is it the most common mate in xiangqi?
It is among the most common, and the most commonly taught, because it needs only two pieces that routinely survive to the endgame.
How do you defend against it?
Keep a spare point for the general, and block the line before the cannon arrives. Badly placed advisors are often why it works. See advisors and elephants.
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