Trapping Pieces in Xiangqi: Winning a Piece With No Escape

Why pieces get stuck on this board

Each piece has a weakness a trapper can use. The Horse moves one point straight and then one point diagonally outward, and if that first point is occupied, the jump is not allowed at all. Stand on that point, the Horse's leg, and you take away two jumps with a single piece. A Horse on the edge file starts with at most four jumps instead of eight, so it takes very little to freeze it.

The Chariot is the strongest piece on the board, but in a corner it has only two lines to use. Close both with protected pieces and every move it has becomes a losing capture. The Cannon moves like a Chariot but captures only by jumping over exactly one piece, so it can never take something standing right next to it. A Cannon deep in enemy territory, with no screens left on its lines, often has nowhere useful to go.

The Soldier is the natural trapper. Once it crosses the river it attacks sideways as well as forward, and bigger pieces often cannot hit back. A Horse can never capture a piece standing directly beside it, and neither can a Cannon. That makes a crossed Soldier the ideal piece to walk up to a cornered victim.

Example one: the Horse on the rim

Black's Horse stands on the left edge, on Black's own bank of the river. Black's edge Soldier is still on its starting point, directly behind the Horse on the side nearer Black's back rank. A Red Soldier has crossed the river and stands on the same rank, two files in from the edge. Red's Chariot is on the second file from the left, back on Red's side on the rank where the Cannons start. Both Generals are at home behind their Advisors and Elephants, and nobody is in check.

Count the Horse's jumps before Red does anything. The long jump toward Black's back rank is not available, because its own Soldier is standing on the leg. The long jump toward Red's side lands on the Chariot's file, where the Chariot takes it. The short inward jump toward Black's side lands right in front of the Red Soldier, which captures forward. That leaves one safe square: the short inward jump toward Red's side, across the river. The engine agrees that it is the only safe move the Horse has.

Now Red plays the quiet move. The Soldier steps one point sideways toward the edge and stands right beside the Horse. Three things happen at once. The Soldier attacks the Horse, because crossed Soldiers capture sideways. It is standing on the leg for both inward jumps, so the safe square disappears. And the Horse cannot hit back, since a Horse never captures a piece directly beside it.

The engine confirms the result. The Horse has one legal move left, the long jump toward Red's side, and the Chariot covers that point. Black cannot save the piece. The Soldier behind the Horse does guard it, so Black may be able to win Red's Soldier back, but that is the most Black can recover in any line. A Horse for a Soldier is a very good deal for Red.

Notice what did the damage. An attack on its own can usually be answered by running away. What decided this one was that the Soldier's step took away the last safe square and delivered the attack in the same move.

Example two: a Chariot shut in the corner

Chariots get trapped when they raid. Here Black's Chariot has broken into Red's bottom-left corner and sits on the point where Red's own Chariot started. Red's Horse is still on its starting point right beside it. Red's other Horse is on the third file from the left on the Cannon rank, and Red's edge Soldier is still at home. Red's left Elephant has moved up to the central point in front of the palace, Red's left Advisor has stepped into the palace centre, and Red's Cannon stands on the Cannon rank just left of centre.

Before Red moves, look at how little the Chariot has. It can go up the edge file to either of the two empty points, take the Soldier on the edge, or take the Horse beside it. If it goes to the upper empty point, the Horse at home takes it. If it goes to the lower one, the other Horse takes it, and that same Horse also guards both the edge Soldier and the Horse on the back rank. Every move lands on a covered point. The Chariot is boxed in, but nothing is attacking it yet.

So Red does not need to trap the Chariot. It only needs to attack it. The Cannon drops two points back along its file to the empty Advisor corner on Red's back rank. With the Elephant gone from its home point, the only piece between the Cannon and the corner is Red's own Horse, so the Cannon now fires over the Horse at the Chariot. It is not check, and it does not need to be.

The engine confirms the rest. Every move the Chariot has still lands on a covered point, and whatever Black plays, the Chariot is lost. Black's best try is to take the Horse beside it and be recaptured by the other Horse, which still leaves Black a Chariot for a Horse down. Every other reply loses the Chariot for nothing.

The lesson for the raider is simple. A Chariot in the enemy corner has two lines. If both are closed by protected pieces, one attacking move ends the story.

Cannons with nowhere to go

Cannons are trapped in their own way. A Cannon that has gone deep to hit an Advisor or an Elephant often ends up with short lines and no screens. Because it cannot capture a piece standing next to it, attackers can walk right up to it, and if the points it can slide to are covered, it is as stuck as the Horse on the rim.

When you hunt a Cannon, count its screens. Its only way to capture its way out is over exactly one piece. Put a second piece on that line, or move the only screen away, and the escape is gone. When an enemy Cannon comes deep into your half, check which of its lines still has a screen, and whether one quiet move can take that screen away.

Setting traps and staying out of them

When you are hunting, look for the enemy piece with the fewest safe squares, not the one that looks most exposed. A piece with one way out is a target. Ask which of your moves takes that last square away, and whether the same move can attack the piece as well. Cheap attackers work best, Soldiers above all, because the trapped piece cannot profitably take them.

Then check the price before you commit. Make sure the trapped piece has no capture that hurts you, such as swapping itself for one of your Chariots, and that your opponent has no check to gain a tempo. If the victim can trade itself off evenly, it was never really trapped.

When you are the raider, count your way home before you go in. Where is your Horse's leg, and which enemy piece could stand on it? Which line will your Chariot use to get back, and can one move close it? A raid that wins a Soldier and loses a Chariot is one of the quickest ways to throw away a good position.

Practise it

Traps are easier to feel than to read about. The 5,000 engine-proven mate puzzles at /puzzles build the same habit of counting a piece's escape squares, with the General as the piece being hunted. When you want to try a trap in a real game, play the computer at any of its eight levels, from Easy to God. A free XiangqiPlay account is all you need to start.