Nine Men’s Morris

How to win at Nine Men's Morris

Nine Men's Morris runs in two phases on a board of twenty-four points. First comes placement: you and the computer alternate putting down nine pieces each. Then comes movement, where a turn is one slide along a marked line to an adjacent empty point. In either phase, three of your pieces on a line form a mill, and each new mill lets you remove one enemy piece. Grind the computer down below three pieces, or leave it with no legal move at all, and you win.

The structure the whole game bends around is the running mill, also called a double mill: two mills sharing one piece, arranged so that sliding the shared piece back and forth breaks one mill and completes the other on alternate turns. A working running mill captures a piece nearly every move, and no ordinary defense survives that bleed. The placement phase, played well, is really a fight over who gets the skeleton of one first.

Placement decides more than people think

Count connections and the board explains itself. The four crossing points, where the midpoints of the middle square meet the spokes, each touch four lines. Most points touch three, and the corners touch only two, which is why experienced players largely ignore corners for their first several placements. A piece on a crossing point sees more mill lines and keeps more escape squares for later, so it works on offense and defense at once.

The classic placement weapon is the fork: a piece dropped so it threatens to complete two different mills next turn. The computer can block only one, so you finish the other and capture. The shape to look for is two of your pieces on one line and two on another, with a single empty point lying on both lines; landing there is the fork. Good opponents see it forming a move early, so the deeper craft is placing quiet, flexible pieces whose double threat only becomes visible once it can no longer be stopped.

Two habits lose the placement phase for beginners. One is grabbing the first available mill: you sink three placements into a single line, collect one capture, and sit with a rigid clump while the computer spreads across the strong points. The other is answering every threat with a pure block. A block that does nothing else falls a move behind; the good defensive piece also builds toward a line of your own.

The moving phase and the endgame

• Open and shut: sliding a piece out of a mill and back in next turn re-forms it for a fresh capture. When the computer sets this up, park a piece in the gap it needs.
• Capture for position, not convenience. Remove pieces on crossing points, or the shared piece of a brewing double mill, before anything nearer to hand.
• Watch total mobility. If all your pieces end up wedged with nowhere to slide, you lose on the spot, and that squeeze usually builds slowly around the inner square.
• Trade down only when ahead. With ten pieces against eight, even exchanges push the computer toward the three-piece cliff faster than they push you.

A widely played variant softens the endgame: a player reduced to exactly three pieces may fly, jumping to any empty point instead of sliding. It sounds generous, but a flying side is one capture from death, so the stronger side still wins with ordinary care.

Older than Rome, solved by computer

Nine Men's Morris is among the oldest board games still in common play. A board is cut into a roofing slab of the ancient temple at Kurna in Egypt, others are scratched into the stone seats of the Roman forum, and the Vikings left one on a plank of the Gokstad burial ship. Medieval masons carved boards into the cloisters of English cathedrals, and the Latin merellus, a game counter, gave the game its other names, merels and morris; in Germany it is Mühle, the mill game. Shakespeare has Titania mention it in A Midsummer Night's Dream, complaining that the nine men's morris is filled up with mud, evidence that Elizabethans also played it cut into village turf. The mathematics closed in 1993, when Ralph Gasser's computer analysis proved the game a draw with perfect play from both sides. That verdict takes nothing away from a real game: one loose placement, and a running mill turns the theoretical draw into a rout.