How do you checkmate with two horses?
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
Coordinate the two horses so their combined coverage removes every escape point at once, since neither horse alone controls a whole line. Two horses is one of the material combinations that forces mate against a bare general, but it takes more care than a chariot mate because each horse only threatens specific points rather than a full rank or file.
Why coordination is everything here
A chariot mate works by controlling whole lines; a horse mate works by controlling specific points, so the two horses need to be placed so that between them every point the general could reach is covered. One horse covers only a handful of points at a time, so even a lone horse, which does force mate against a bare general, leans on its own general to take away the file. What an emptier board gives the horse is freedom rather than reach, which is why a horse improves so much as material comes off the board: fewer pieces are left to block its legs.
Watch your own legs
Because a horse's own move can be blocked by a piece on an adjacent point, including your other horse, check that neither horse is accidentally standing in the other's way before committing to the final position.
Related questions
Is this mate common in real games?
Less common than chariot mates, since two horses without other material is a fairly specific reduced position.
Does the general help here too?
Yes, as with most bare-general mates, it denies a file the horses cannot otherwise cover.
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