Nine Men’s Morris is a two-player game on a board of three nested squares with 24 points, in which each player places nine pieces and then slides them along the lines, removing an opponent piece whenever they make a line of three called a mill. There are 16 possible mills on the board. A player loses on being reduced to two pieces or being unable to move.
A nine-piece placing-and-sliding game on a scratched board, with a full rule set and a way to mark the board.
The Board
Scratch three squares, one inside another, and join the midpoints of their sides with four lines. A convenient method is a 7 × 7 grid of coordinates 0 to 6:
- Outer square: corners and midpoints at coordinates 0 and 6, midpoints at 3
- Middle square: at coordinates 1 and 5
- Inner square: at coordinates 2 and 4
- Connecting lines: from (3,0) to (3,2), (3,4) to (3,6), (0,3) to (2,3), and (4,3) to (6,3)
Each square has 8 points (4 corners and 4 midpoints), so there are 3 × 8 = 24 points. The possible mills: each square has 4 sides carrying 3 points, 3 × 4 = 12; the 4 connecting lines each carry 3 points (one per square), 4 more. That is 12 + 4 = 16 mills.
Rules
Two players, nine pieces each, in two clearly different kinds.
Phase 1, placing. Players alternate putting one piece on any empty point. This takes 9 placements each, 18 in all. Pieces already placed do not move in this phase.
Mills. A mill is three of your own pieces in a straight line along a line of the board (not around a corner). Whenever you form a mill, remove one opposing piece from the board. You cannot remove a piece that is in a mill unless every opposing piece is in a mill.
Phase 2, moving. When all pieces are placed, players alternate sliding one piece along a line to an adjacent empty point. Forming a mill, including by moving a piece out of a mill and back, removes an opposing piece.
Winning. A player loses on being reduced to two pieces, or on having no legal move. Some groups add a rule that a player reduced to three pieces may “fly” a piece to any empty point; agree beforehand whether to use it.
Strategy That Helps
- In placing, mobility matters more than quick mills. A piece that is boxed in is useless in phase 2.
- Block the opponent’s near-mills.
- Hold the points where four lines meet: the midpoints of the middle square have the most connections.
With perfect play the game is a draw, as I recall from work that solved it in the 1990s (Gasser, 1996; recalled, verify). It still plays well between people.
What Dates It
The parent article states the game is “over 3,000 years” old. I could not substantiate that: boards of the Roman period and later are well documented, and claims of much greater age rest on disputed marks. Say simply that it is an old game.
What You Need
- A flat surface and a pointed tool or charcoal
- 9 + 9 pieces of two kinds
- Agreed rules, especially about flying
Method: A First Game
Step 1: Scratch the board using the 7 × 7 coordinates.
Step 2: Place pieces alternately, trying to make mills while blocking the opponent.
Step 3: When all 18 are down, slide pieces to open and reclose mills.
Step 4: Note the removals and count pieces until one side has two.
Common Mistakes
- Filling the board with no free moves. The blocked player loses.
- Removing a piece from a mill when others are available. The rule forbids it.
- Forgetting that a mill must lie on a line. Three pieces around a corner are not a mill.
What’s Next
- Learn next: Mancala Variants — a counting game
- Combine with: Board & Strategy Games — choosing among the four