Palcorner Horse Checkmate: How the 挂角马 Mate Works

Reading the name and the geometry

挂 means to hang and 角 means corner, so the name pictures a Horse hanging on the corner of the palace. Palcorner is simply a contraction of palace corner. Chinese glossaries also list the name 士角马, the Advisor-corner horse, because the point sits on the same file as an Advisor's starting point.

Why that point? From a front corner, a Horse reaches the General's home point in one leap: two steps toward the back rank and one step toward the centre. Like every Horse move in Xiangqi, the leap can be stopped at its leg. Here the leg is the point directly between the Horse and the back rank, the middle point of that side of the palace. If anything stands there, friend or foe, the Horse is hobbled and there is no check.

From the same corner, the Horse also reaches a back-rank point just outside the palace and, when the middle of the palace's front edge is empty, the middle point of the opposite side edge. What it never touches is the palace centre or either back corner. That is the whole story of this mate in one sentence: the Horse gives the check, and something else has to take away the General's exits.

A mate you can set up in half a minute

Here is a clean version to put on a board. Black's General stands on its home point in the middle of the back rank. Both Black Advisors are still on their starting points in the back corners of the palace, and a Black Elephant sits on the middle of the palace's front edge, two points in front of the General. Red has a Chariot on Black's second rank at the far right edge of the board, a Horse on Black's side of the river on the rank nearest the river, on the third file from Red's left, and the General on its home point. Red is to move.

The Horse jumps forward onto the palace's front corner on Red's left. That is check, and it is mate. The General cannot step sideways, because its own Advisors fill both back corners. It cannot step up into the palace centre, because the Chariot sweeps the whole second rank. No Black piece can capture the Horse, and none can reach the leg point to block it. We ran the position through the rules engine that powers XiangqiPlay, and Black has no legal move.

The Elephant is only there to keep the central file closed. Without it the two Generals would face each other on an open file, and the position could not arise.

A second version needs even less. Keep Black's General and both back-corner Advisors, put the Red Horse straight onto the palace's front-left corner, put a Red Soldier on the middle of the palace's front edge, and leave the Red General at home. With Black to move, this is already checkmate: the Soldier covers the palace centre, the Advisors block the sides, and the Horse checks. Remember it for endgames where a Soldier has walked all the way up the central file.

Walking the Horse to the corner

In a real game nobody hands you the corner. The usual route is to bring a Horse across the river and then hop it sideways on Black's half until a jump to the corner appears. From the rank nearest the river on Black's side, a Horse on the central file, or on either file just outside the palace, is one leap away from a front corner, provided the point directly in front of it is empty.

Timing matters more than the route. The check hurts most when the General is still on its home point and both Advisors are on the back corners, because then the only exit is straight up into the palace centre. Control that point before you jump, with a Chariot on the second rank or a Soldier on the palace's front edge.

A pin can do the rest. If Red has a Cannon on the central file with two Black pieces standing between it and the General, neither of them may move off the file, because the other would be left as a lone screen and the Cannon would be giving check.

Here is a tested case. Black's General is at home, one Advisor sits in the palace centre, the other on the back corner on Red's left, and an Elephant stands on the middle of the palace's front edge. Red has a Cannon on the central file on Red's own side of the river, on the rank nearest the river, a Horse on the rank nearest the river on Black's side, on the file just right of the palace, and the General at home. The Horse jumps to the palace's front-right corner. It is check, and the centre Advisor, normally the guard of that corner, is not allowed to take the Horse. The General has to step into the right back corner, its only legal move.

How Black keeps the corners shut

The best defensive habit is an Advisor in the palace centre. From there it guards both front corners at once. Take the first example and move Black's right-hand Advisor from its back corner into the palace centre: the same Horse jump is still check, but now the Advisor simply captures the Horse, and the General could also step across into the empty back corner. That is why the centre Advisor is the standard answer whenever an enemy Horse starts circling.

The second defence is the leg. A Horse on the front corner needs the middle point of that side of the palace to be empty. Advisors and Elephants can never stand there, so this job falls to a Chariot, Horse or Cannon parked on the point, and a well-placed one takes the sting out of the check before it happens.

Finally, watch the approach. A Horse that is one leap from your palace corner is a threat now, not in three moves. Chasing it, occupying the point in front of it, or trading it off before it arrives is nearly always cheaper than defending the mate once it is on the board.

Mistakes that let the General walk away

Jumping too early is the classic error. A palcorner check with the palace centre unguarded just lets the General step up a rank, and the Horse has spent several moves for one harmless check.

The second mistake is forgetting the leg. You count the General's exits carefully, then discover that your own Soldier or Cannon is standing on the leg point and the Horse was never giving check at all.

The third is treating the two corners as interchangeable. Each one needs a different leg point to be empty, and each covers a different point on the far side of the palace, which matters the moment the General starts running. Check both before you commit.

Once this mate feels familiar, look at its relatives. The trough horse, 卧槽马, checks the same home point from Black's second rank, and Chinese texts describe a follow-up called 八角马, the eight-corner horse, in which the palcorner Horse drives the General onto the palace corner diagonally opposite it.

Drill the corner jump

Patterns like this stick through repetition rather than reading. XiangqiPlay's free puzzle library has 5,000 engine-proven mate puzzles to work through, and when you want to try the corner jump in a live game, a free account lets you play the computer at any of its eight levels (Easy to God).