The Edge Cannon

Why move a cannon to the edge?

The first move clears the way for Red's chariot and horse. Red plays 炮二平一 (C2=1), or 炮八平九 (C8=9) from the other wing. On this page the cannon goes from h2 to i2, where it attacks Black's soldier on i6 over Red's own soldier on i3.

The board below shows how the move makes room. After it, Red's horse comes out from h0 to g2, and the chariot steps from i0 to h0. There the chariot attacks Black's cannon on h7 along the file that Red's cannon has left. These three moves form Red's three-step tiger (三步虎, sanbuhu).

The edge cannon is one of the less common cannon openings. In the ECCO, the Chinese system of opening codes, it has a single code, A03.

The course line, move by move

The board plays the line that Xiangqi Arena's opening course teaches for the edge cannon. It starts with the edge cannon, and a computer engine continued it from there. The course teaches it on the left wing, and this page mirrors it onto the right wing, where the archive and the standard names of the variations put the opening.

As you step through it, watch the h-file. Red's first three moves, the cannon to i2, the horse to g2 and the chariot to h0, are the three moves of the three-step tiger. Black's chariot comes to the same file on h9. By the end nothing stands between the two chariots, so Black's chariot can take Red's chariot on h4.

Archive lines with an edge cannon

No archive game opens with the edge cannon, but in other games a cannon reaches an edge file after different first moves. The three named lines below come from such games: Red's cannon after a horse move, Red's second cannon in a central cannon game, and Black's cannon as one of the three moves of a three-step tiger.

Which line to study depends on what you play. If you like to bring out a horse first as Red, start with the first line. If you open with the central cannon, look at the five-nine cannons, and if you meet the central cannon as Black, look at the third line, where Black builds a three-step tiger.

Ideas and principles

The main idea of the edge cannon is the three-step tiger, a set of three moves in a row that either side can make: a horse comes up, the cannon moves to the edge and the chariot comes straight out. For Red these are 马二进三 (H2+3), 炮二平一 (C2=1) and 车一平二 (R1=2). Together they bring a chariot into play by the third move.

The course line plays all three as Red's first three moves, with the cannon first. The chariot then stands on h0, and the h-file is open in front of it as far as Black's cannon on h7.

Xiangqi Arena teaches five principles for the opening: bring the chariots out quickly, do not move one piece again and again, do not grab soldiers, keep both wings in balance and do not expose the general. You can see three of them in the course line. Each side has a chariot out by its third move, and the only piece that moves twice is Red's chariot. Red's cannon attacks the soldier on i6 from the first move, yet neither side captures anything in the twelve moves.

Common mistakes

The cannon on i2 attacks Black's soldier on i6 from the first move, and taking it at once can look tempting. In the course line Black's chariot stays in the corner until Black's third move and guards that soldier down the edge file. If your cannon takes the soldier, the chariot takes your cannon, and you have given a cannon for a soldier. Bring out the horse and the chariot first, as the course line does on Red's second and third moves.

As Black, watch your cannon on h7 once Red's chariot reaches h0. The chariot attacks it along the open h-file, and at that moment nothing guards it. If your next move does not deal with the threat, the chariot takes the cannon for free. In the course line Black's chariot steps to h9 at once and guards it.

As Red, keep watching the h-file at the end of the line. Your chariot on h4 attacks Black's cannon on h7, and Black's chariot stands behind that cannon on h9. When the cannon steps aside to i7, the two chariots face each other: yours has no guard, while Black's horse on g7 guards the one on h9. If your next move does not deal with this, Black's chariot takes yours for nothing.

The edge cannon in the archive

None of the archive's 29,164 games between human players opens with the edge cannon, so this page has no results to show for it. Cannon moves to the edge do appear later in archive games, as the three named lines above show.

With no archive games to follow, the opening course is the place to practise the edge cannon. Step through the course line until the moves come easily, then try the course's two drills: in one you play Red's moves yourself, and in the other you defend against the opening as Black.

The course and its drills play the line on the left wing, so there the first move is 炮八平九 (C8=9). After the drills, try the edge cannon in a few games against the computer. It will not win games by itself, but it brings your chariot into play by the third move.