What is a fortress in a xiangqi endgame?
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
A defensive setup the attacker cannot break through even with extra material. The clearest example is two advisors and two elephants against a lone chariot: the chariot is materially ahead by a wide margin and still, by the standard verdict, cannot force a way in, because every point the defence needs to hold is actually covered.
Why fortresses work despite the material gap
A fortress does not depend on counting pieces; it depends on structure. As long as the defender's advisors and elephants sit on the right points, the lone chariot has nowhere to break through that is not already guarded. This is exactly why xiangqi endgames turn on structure rather than raw material more than people expect.
Recognising when you are inside one
If you are defending and your advisors and elephants remain intact, do not panic at a growing material deficit; check whether the specific structure you are in is one of the known drawn ones first. Structure, not material count, decides the result here.
Related questions
Can a fortress ever be broken?
Yes, usually only by removing one of the defending pieces, an advisor especially, which is why attackers target them specifically.
Is this the same idea as a fortress in chess?
The same underlying concept, an unbreakable structure regardless of material, applied to xiangqi's specific defensive pieces.
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