Why do elephants matter more as the board empties?
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
Because with fewer pieces left to cover for them, the elephants' specific job becomes the entire defensive plan rather than a small part of one. In a full position, several pieces overlap in what they can cover; in a sparse endgame, the elephant's role of denying key points to horses and soldiers is frequently the only thing standing between a level position and a loss.
What elephants are actually for
An elephant covers the points a horse wants to land on and the approach a soldier is using, and it does that job whether or not anything else is on the board. As the position empties, there is less redundancy, so a missing or badly placed elephant is exposed far more clearly than it would be earlier.
The practical consequence
Do not trade elephants away casually heading into an endgame with horses or soldiers still on the board, even if the trade looks neutral in the moment. See advisors or elephants, which to keep for how this weighs against the equivalent question for advisors.
Related questions
Do elephants matter against a chariot endgame too?
Less directly, since chariots are answered mainly by advisors, but an intact full defence still helps generally.
Should I ever trade an elephant on purpose?
Against a lone cannon, removing the elephant that is serving as its screen can be worth more than the piece.
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