Can the flying general rule ever help the defender rather than the attacker?
These answers restate the rules implemented by our open-source engine, which follows the WXF laws for movement, checkmate and both repetition rulings: a side that forces a repetition by perpetual check or perpetual chase loses rather than drawing. The chase half has not been validated against the official casebook. Where an answer refers to a specific position, that position lives on the linked reference page, where the build verifies it before publishing.
Direct answer
Yes, occasionally. The rule is usually described as an attacking weapon, because it hands the stronger side a free extra piece in a bare endgame, but it is symmetrical. The defending general equally denies the attacking general its file, and an attacking piece standing alone between the two generals cannot leave that file. What the rule never does is stop other pieces using the file: it only forbids the generals facing each other.
Why this is rare but real
Most of the time a defender is trying to survive, not restrict the attacker's pieces, so the situation does not come up often. But in a sparse position an attacking horse that has ended up alone between the two generals cannot move at all, and an attacking chariot, cannon or soldier there can only move along the file, which can be exactly the tempo the defence needed.
Why it is still mainly an attacker's tool
The rule helps whichever side is better placed to exploit an open file, and in the great majority of bare endgames that is the stronger side pressing forward, not the weaker side holding on. Treat the defensive case as a genuine but unusual exception rather than a reliable resource to plan around.
Related questions
Is this the same mechanism as the attacking version?
Yes, exactly the same rule, see how the flying general rule is used as an endgame weapon for the more common, attacking case.
Should a defender ever try to engineer this?
Only opportunistically, if it happens to be available, it is not something worth building a defensive plan around from scratch.
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