The Single Horse Defence

Which horse guards the centre?

Red's first move, 炮二平五 (C2=5), puts a cannon on e2, where it attacks Black's centre soldier on e6 through Red's own soldier on e3. On the board, Black answers with 马8进7 (H8+7), so the horse on g7 guards that soldier. Two moves later, 马2进1 (H2+1) takes the other horse to the edge at a7. With one horse on the seventh file and the other on the edge, Black has the single horse defence.

The defence can also start on the other wing, as in the archive's lines further down, where 马2进3 (H2+3) brings a horse to c7 to protect the centre soldier. After Red's 马二进三 (H2+3), Black forms the defence in one of two ways: 马8进9 (H8+9) takes the second horse to the edge at i7, or 车9进1 (R9+1) lifts the chariot and leaves the second horse at home.

The board plays the six moves up to 马2进1 (H2+1) and then draws the guard line from the horse on g7, through its leg on f7, to the soldier on e6. The horse on a7 gets no such line, because from a7 it cannot reach e6.

The course line, move by move

The walkthrough below plays the line that the opening course on Xiangqi Arena teaches for the single horse defence. The line starts with the defence's standard moves, and a computer engine continued it from there. The board shows its first twelve moves, six for each side.

In these moves each side brings out both horses and one chariot. On Red's sixth move, the cannon on b2 crosses the river to b7 and attacks the horse on g7, the piece that guards the centre soldier. Black's last move puts an elephant on e7, in the cannon's path, so the cannon attacks the elephant in place of the horse.

As you step through the moves, ask what each moved piece guards and attacks. In the Learn section, the opening course plays the whole line, and its drill lets you meet the defence from Red's side: you play Red's moves and the board answers with Black's.

Black's replies in the archive

The board in this section starts after 炮二平五 (C2=5) 马2进3 (H2+3) 马二进三 (H2+3), with Black's first horse on c7. In the archive, 2,684 games reached this position. The arrows show Black's three most common replies there, each with its share of those games, and a fourth arrow shows 车9进1 (R9+1), which forms the defence with the second horse left at home.

The three named lines below start from the same position. Two of them play 车9进1 at once and part on Black's third move. The third begins with 炮8平6 (C8=6), the most common reply on the board, and lifts the chariot one move later. If you want a chariot at work early, the horizontal chariot reaches d8 on Black's third move and attacks Red's advisor.

Ideas behind the defence

The single horse defence is one of the four great defences (四大布局, sida buju), the four common ways of opening that the second player generally uses against the central cannon. The other three are the same-direction cannons (顺手炮, shunshoupao), the screen horses (屏风马, pingfengma) and the counter-palace horse (反宫马, fangongma). In the ECCO, a code list of xiangqi openings, the central cannon against the single horse defence has the codes B10 to B14. They belong to class B, which also covers the central cannon against the counter-palace horse and others.

The set-up keeps Black's pieces flexible, but it protects the centre soldier less well than the screen horses do. On the board in the first section, a single guard line reaches e6, from the horse on g7, while Red's cannon on e2 has attacked that soldier since the first move.

The defence suits players who like flexible pieces and keep a close watch on the centre. If you want both horses guarding the centre soldier, choose the screen horses.

Common mistakes

A common mistake is to count the edge horse as a second guard for the centre. From a7 it cannot reach e6, so the soldier there depends on the horse on g7 alone. When Red's cannon reaches b7 in the course line, it attacks that horse while nothing guards it, and Black blocks the attack at once with the elephant from c9 to e7. Play elsewhere instead, and the cannon takes the horse and leaves e6 with no guard.

Another mistake is to bring out horses, cannons and soldiers while both chariots wait in their corners. In every line on this page, Red's chariot reaches h0 early and attacks a piece at once. Black keeps pace: the course line moves a chariot to h9 on Black's second move, where it guards the cannon on h7, and all three named lines lift one with 车9进1 (R9+1). A chariot left in its corner attacks nothing, so the first of the five opening principles is to bring the chariots out early.

If you play Red, the centre soldier can look like easy prey, since only one horse guards it. Taking it is a mistake: if the cannon on e2 takes the soldier on e6, the horse on g7 takes the cannon, and Red has given a cannon for a soldier. In the course line the cannon stays on e2 and keeps its aim on e6 while Red brings out the other pieces. It is one reason the opening principles say not to grab soldiers.

The single horse defence in the archive

In the archive's games with the single horse defence, Red won 49% and Black 27%, and 24% were drawn. Across all 29,164 games between human players in the archive, Red wins 37% and 36% end in a draw.

A game with this defence lasts 43 moves on average. As Red, Lü Qin faced it in the most games, 10. As Black, Tao Hanming played it in the most games, 21.

At the end of this section you can replay one archive game with this defence. Then try it as Black in a few games against the computer, watching the horse that guards the centre. The single horse defence will not win games by itself, but it gives you a flexible answer to the central cannon.