Horse behind cannon (馬後炮)
Every position, move and legality claim on this page is verified programmatically against our open rules engine, which implements the WXF laws and is tested against the official 110-diagram repetition casebook.
Direct answer
In 馬後炮 the horse stands directly in front of the cannon on the same file, so the cannon checks the general through its own horse. The horse covers the two points the general would step sideways to, and the point between is still on the cannon's line, so the general has nowhere legal to go.
The pattern
The name says the arrangement: the cannon sits behind the horse. The cannon needs exactly one piece between it and its target, and here that piece is its own horse, which is why the two work together instead of getting in each other's way.
Red to play. One move finishes the game.
Red to play and mate in one.
Xiangqi position. Red: horse e7, cannon a5, general d0. Black: general e9. Red to move.
Why the general cannot escape
Work through the general's options one at a time, because that is what makes the pattern stick in memory:
- Sideways. Both points beside the general are horse moves away from the horse. The horse covers them from in front.
- Forward, toward the cannon. Still on the same file, and the horse is still the screen, so the cannon still gives check.
- Capturing the horse. Not possible from where the general stands. The horse is two points away, not one.
That is the whole mate. It needs two pieces and no support, which is why it appears in games at every level.
Building it in a real game
The horse arrives first almost every time. It takes three or four moves to reach a point in front of the enemy palace, and it can rarely be chased away once it is there, because the points that attack a horse are exactly the points a defending general cannot reach.
The cannon is the fast half. It can swing onto the file in one move from a long way away, which is why the mate so often looks sudden. If your opponent has a horse planted in front of their general, count the cannon moves before you do anything else.
The defence is to block the file or to give the general a spare point early. An advisor in the wrong place makes this mate possible, and an advisor in the right place makes it impossible.
Common mistakes
Putting the cannon in front of the horse
Then the horse is behind the cannon and the cannon has no screen. The order in the name is the whole pattern: horse first, cannon behind it.
Letting a second piece onto the file
The cannon needs exactly one piece between it and the general. A second one, from either side, switches the check off.
Chasing the general before the horse arrives
Checks that move the general to a safer point make this mate harder, not easier. Set the horse first, then bring the cannon.
Related questions
What does 馬後炮 mean?
It reads literally as cannon behind horse, which is the arrangement of the two pieces. The horse is in front, the cannon behind it on the same file, and the horse serves as the screen the cannon needs.
Why is horse behind cannon so common?
It needs only two pieces, no other support, and both of them are pieces that survive into the endgame. It is also hard to defend against once the horse is placed, because the horse covers the escape points from a distance the general cannot attack.
How do you defend against it?
Keep a spare point for the general inside the palace, and block the file before the cannon arrives rather than after. Advisors matter here: see advisors and elephants.
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