Can a cannon attack two pieces at the same time in xiangqi?
These answers restate the rules implemented by our open-source engine, which follows the WXF laws and is regression-tested against the official 110-diagram repetition casebook. Where an answer refers to a specific position, that position lives on the linked reference page, where the build verifies it against the engine before publishing.
Direct answer
Yes. A cannon sits at the centre of up to four lines, and if two of those lines each already carry exactly one screen with an enemy piece beyond it, the cannon is threatening both simultaneously. Answering one capture does nothing to stop the other, which is exactly what makes a cannon fork so effective.
Why this is easy to miss
Chess players scan for one piece attacking one square at a time out of habit. A cannon's double threat depends on the state of two separate lines, each of which can change independently, so the fork can appear the instant a screen lands on the second line, without the cannon itself moving at all.
Defending against it
If a cannon threatens two of your pieces at once, look first at whether you can remove one of the screens rather than only at whether you can save one of the pieces. Removing a screen kills the threat on that entire line in one move, which a piece-by-piece rescue cannot match.
Related questions
Does the cannon need to move to create a double threat?
No, an opponent's own move that adds a screen to a second line can create the fork without the cannon doing anything.
Is a cannon fork always winning material?
Usually, if both targets are undefended and roughly equal in value, but check what each side can actually do about it before assuming.
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