Two ghosts knocking at the door xiangqi players call 二鬼拍门 uses two Soldiers to freeze the General. A verified mate, the setup, defences and mistakes.
Two ghosts knocking at the door (二鬼拍门, èr guǐ pāi mén) is a xiangqi attacking pattern in which two Soldiers reach the middle points of both sides of the enemy palace. From there they cover the palace centre and both back corners, freezing a General on its home point so that one more attacker can finish it off.
It is mostly an endgame weapon. Soldiers move slowly and never go backwards, so by the time two of them have walked all the way to the palace, most of the heavy pieces have usually been traded. When they do arrive, they are worth far more than their size suggests.
Why the Soldiers are ghosts
In Chinese chess slang the Soldier is often called 小鬼 (xiǎo guǐ), the little ghost or little imp, so 二鬼 simply means two Soldiers. 拍门 is to bang on a door with the flat of your hand. The palace is the General's house, the two Soldiers stand at its gate on either side, and whoever is inside can hear them pounding.
Definitions vary a little. Most Chinese lists of basic mates describe two Soldiers breaking into the palace and locking both rib files, the palace's side files, before other pieces finish the job. A few glossaries stretch the name to cover two Chariots, or a Chariot and a Soldier, pressing on the same points. You will also meet the form 双鬼拍门, which means the same thing. This article sticks to the Soldier version, the one you are most likely to see.
Three points, two Soldiers
A Soldier that has crossed the river moves one point forward or one point sideways. Put Red Soldiers on the middle point of each side of Black's palace and count what they control. Each covers the back-rank point straight ahead of it, which is a back corner of the palace, and each covers the palace centre with its sideways step. Between them they hit all three points around a General on its home point.
Chinese writers like to point out a second effect. Those two points are also the eyes of Black's Elephants, the points an Elephant has to pass over on its way from the back rank to the front of the palace. An Elephant whose eye is occupied cannot move that way. With a Red Soldier on the middle of the palace's left side, Black's left Elephant, still on its starting point, can no longer step to the front centre of the palace to help.
The Soldiers also threaten to capture an Advisor at almost any moment, which is why the pattern works as a battering ram against the Advisors as much as a mating net.
A mate to set up
Put Red at the bottom and read left and right from Red's side. Black's General is on its home point with an Advisor on each back corner of the palace. That looks tidy, but nothing else is nearby. Red has Soldiers on the middle points of both sides of Black's palace, a Chariot on Red's soldier rank on the right rib file with that whole file empty up to the Soldier, and its General on the left back corner of its own palace.
Before Red moves, notice that Black's General has no legal step at all. The palace centre is covered by both Soldiers, and the two corners are occupied by its own Advisors.
Red now plays the right-hand Soldier forward, capturing the Advisor on the back corner. The Soldier stands right beside the General and gives check sideways. The General cannot take it, because Red's Chariot, looking up the file the Soldier has just left, guards that point. It cannot step forward to the palace centre, which the other Soldier still covers. Its other side is blocked by its own Advisor, and that Advisor's only move, to the palace centre, does nothing about the check. Checkmate, and XiangqiPlay's rules engine confirms it.
The Chariot is not essential. Take it away and put Red's General on the right back corner of its palace instead, with the file open all the way. The same capture is mate, because taking the Soldier would leave the two Generals facing each other.
Marching the ghosts in
The hard part is getting there, and a few habits help.
Push the Soldiers as a pair. Two Soldiers side by side on the same rank, once they have crossed the river, protect each other, because each covers the point next to it. Separated, each one is a target.
Take the palace side points last. A Soldier on the middle of a palace side is no longer protected by its partner, which now stands two files away. That is fine if another piece covers it, or if the defender's General cannot reach it, but it is a real weakness if the General sits on the back corner right next to it.
Bring a helper. Two Soldiers alone rarely mate a General that still has Advisors and room. A Chariot, a Horse, a Cannon or your own General on an open file supplies the final check or the protection that makes a Soldier's check stick.
Answering the knock
The Advisor on the palace centre is the key defender. Change one thing in the worked example: put one Black Advisor on the palace centre and the other on the back corner on Red's right. Red's Soldier can still capture the corner Advisor with check, but it is no longer mate, because the central Advisor takes the Soldier back; the engine shows that recapture as Black's only move. From the palace centre an Advisor reaches all four corners, so a Soldier that lands on one of them can be captured. Do not take too much comfort from this particular diagram, though. With so little left around Black's General, the engine finds that Red's Chariot still forces mate in two more moves. Once two Soldiers and a Chariot are sitting outside a bare palace, the defence has come too late.
So the real defensive work happens earlier: stop the Soldiers before they arrive. They cannot retreat, so a Soldier attacked on its way up the board must be defended or lost. Trade them off, or keep a piece ready to capture the first one that comes close. Watch the elephant eyes too: once enemy Soldiers sit on them, your Elephants lose their route to the centre, so place them before the door is blocked.
Counterattack counts as defence here. Soldiers are slow, and every move the attacker spends walking them forward is a move for your own threats.
Mistakes with the ghosts
Rushing one Soldier into the palace alone is the usual error. A single Soldier on a palace side point is often just captured by the General or an Advisor.
Forgetting that the Soldier's check needs support is the next. A Soldier giving check stands next to the General, and an unprotected checker can be taken. Before pushing, ask what guards the point your Soldier will land on.
Pushing a Soldier onto the back rank too early also wastes it. A Soldier on the last rank can only move sideways and no longer covers the palace centre, so one standing on the middle of a palace side is usually far more useful than one tucked into a corner.
Try it yourself
Soldier mates reward patience more than calculation. XiangqiPlay's free library of 5,000 engine-proven mate puzzles has plenty of finishes where a humble Soldier gives the last check, and with a free account you can practise walking two ghosts up the board against the computer at any of its eight levels, from Easy to God.
XiangqiPlay Team
XiangqiPlay newsroom
