What is a cannon fork 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
A cannon fork is one move that creates two separate capture threats simultaneously, using two different lines from the same cannon. It usually happens when a cannon moves to a point that is exactly one screen away from two valuable pieces on two different lines, and the defender cannot save both.
Why cannons fork differently from horses
A horse forks by reaching a single square that attacks two pieces directly. A cannon forks by reaching a square from which two separate lines, each already holding a single screen, point at two separate targets. The mechanism is different but the result, an unanswerable double threat, is the same idea covered generally in the site's fork tactics.
Spotting one before it happens
Before moving a cannon to a seemingly ordinary square, check every line it will control from there, not just the one you intended. A fork often looks like a routine repositioning move until you notice the second line was already primed with a screen.
Related questions
Is a cannon fork the same as a battery?
No. A battery is two pieces working together on one line; a fork is one piece threatening on two separate lines at once.
Can you fork with a cannon that has no screen on either line?
No, both lines need their own single screen already in place, or the cannon is threatening nothing on that line.
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