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Epaminondas is a strategy board game invented by Robert Abbott in 1975. The game is named after the Theban general Epaminondas, known for the use of phalanx strategy in combat. The concept of the phalanx is integral to the game. The Theban general who invented the phalanx, a formation he used to defeat the Spartans in 371 B.C. The term "phalanx" is used in the game to describe a certain arrangement of pieces that can move and capture as a single unit.

While the original version used an 8×8 checkerboard, the current game uses a 12×14 board and different rules for capture. When published, it claimed to be one of the first modern games to acknowledge the name of its inventor in its rules.

Epaminondas is played on a 14 x 12 board with 28 black pieces and 28 white pieces. A checkered board is helpful for visualizing diagonals. The pieces are flat, like checkers. Black and white take turns to move. White moves first. Broadly speaking, white moves his pieces up the board to occupy black's back rank, and black moves his pieces down the board to occupy white's back rank.


In the game, a phalanx is a horizontal, vertical, or diagonal line of two or more stones of the same color, with no empty spaces or enemy stones between them. A stone may belong to more than one phalanx, depending on the direction considered. A phalanx is defined as a connected group of two or more pieces in a straight line, either orthogonally or diagonally. A piece may belong to several phalanxes in different directions.

On each turn, each player moves one friendly phalanx. A phalanx moves over the line that defines it, with a moving range up to the number of its pieces. E.g., a phalanx with four pieces can move up to four squares along its line. If the phalanx, while moving, encounters an enemy phalanx with a smaller number of pieces, that phalanx is captured. In this case, the friendly phalanx stops with its first piece on the square of the first enemy piece of the captured phalanx. In all the other cases, the moving phalanx must always move over empty squares. Capturing is not mandatory.

If a player, at the beginning of his turn, has more friendly pieces in his last row than his opponent does, he wins the game. E.g., if White, at the beginning of his turn, has three white stones in the last row, and Black only has two black stones in his last row, then White wins the game.

An isolated piece is a phalanx of size one. So it can move to any adjacent empty square. Isolated pieces cannot capture (because captured phalanxes must always be smaller). It is not mandatory to move an entire phalanx. A player with a phalanx of five stones, may decide to move, say, just the first three stones (i.e., he moves a phalanx of size three). Phalanxes may move to either direction along the line (e.g., a horizontal phalanx may move to the right or to left).

The winning condition is verified before the player begins his turn. If, after the move, a player has more pieces than the adversary, the adversary still has one chance to balance the position and continue the game (either by capturing some enemy pieces from his first row or by adding friendly pieces to his last row). The next diagram shows some phalanx moves. Starting the game, White moved one square the phalanx defined by f1-g2, putting the first phalanx stone at h3. We describe this move as f1,g2-h3. Next, Black moved e12,f11h9. White replied with a vertical phalanx, from h1 to h3, moving it to the maximum of three squares, i.e., h1,h3-h6. The result of these moves was:
In the next diagram there is an example of phalanx capture. The black phalanx h12,h9, with four stones, moves three squares down until it finds the first white stone of a phalanx with size three. Since the white phalanx is smaller, it is captured and removed from the board. If the white phalanx had four or more stones, this move would be invalid.

The next illustration shows a position where White has the advantage. The horizontal white phalanx in the first row is made of seven pieces, it is able to resist the attacks of the two potential black phalanxes (e5,c3 and e5,e3.) But the horizontal black phalanx at row 12, with six pieces, cannot avoid the white double attack (a8,a9 and j5,j8), because these are separated by eight columns. White starts with j5,j8-j12, capturing one black stone. Black must capture that white stone at row 12 (or else, he would lose immediately) and White continues these captures, eroding the black phalanx. When these moves end, the other white phalanx at a8,a9 can move to row 12 without resistance.


Each turn a player must either move a single piece one square in any direction to an empty square or move a phalanx. It is not permitted to pass.

When a phalanx moves, all the pieces in the phalanx move an equal number of squares in the same direction in a straight line. The direction of movement must be either forward or backward along the line of orientation of the phalanx. The number of squares moved by each piece must be equal to or less than the total number of pieces in the phalanx.

If the board extended far enough to the right, the phalanx could move in that direction, too. (For reasons of space, the only example given is of a horizontal phalanx, but the same rules equally apply to vertical and diagonal phalanxes.)

A phalanx can be split up to move. In this case, the number of squares it can move is equal to or less than the total number of pieces in the moving phalanx. Figure 2 (v) shows the position after a two-piece phalanx has split off from the three-piece phalanx of (i) and moved two squares. It could not move further.

A phalanx cannot move off the board or onto or over a square occupied by a friendly piece. Under certain conditions, when capturing, the lead piece of a moving phalanx may move onto a square occupied by an enemy piece. At no other time may a phalanx move onto or over an opposing piece.
It is logically consistent (and probably helpful) to think of a single piece as a phalanx of one.
White moves first; then turns alternate.
  • A player can move a single piece one space in any direction (the same as a king in chess).
  • A player can, instead, move a phalanx any number of spaces equal to or less than the number of pieces in the phalanx. All the pieces in the phalanx must all move in the same direction, and that direction must be along the line of the phalanx. (For example, a phalanx of three stones along a diagonal can move three, two, or one spaces along that diagonal.)
    • A player does not have to move an entire phalanx; the player can split the phalanx into two parts as long as the subset moved is continuous and moves no further than its length.
    • A phalanx cannot move through or across pieces of the same color.
  • To keep the game from ending in a draw due to copycat moves, there is an additional rule: no player may move a piece onto their opponent's home row if that move creates a pattern of left-to-right symmetry on the board.

Under certain conditions the lead piece of a moving phalanx can move onto a square occupied by an enemy piece. The phalanx's movement must then stop.

 In order to move onto this square occupied by an enemy piece, the number of pieces in the phalanx to which this enemy piece belongs, extending back in the direction of movement of the moving phalanx, must be strictly less than the number of pieces in the moving phalanx.

In this case, the enemy piece is captured together with all pieces in the phalanx to which it belongs, extending back in the direction of movement of the moving phalanx. Captured pieces are removed from the board and take no further part in the game. 

As a corollary of these capturing rules, a single piece, as a phalanx of one, can never effect a capture because it can never outnumber an opposing phalanx.

A player wins when, at the start of their turn, they have strictly more pieces on their opponent's home row than the opponent has on the player's home row. (To clarify, if at the beginning of Black's turn, Black has more pieces on row A than White has on row Z, Black wins. If at the beginning of White's turn, White has more pieces on row Z than Black has on row A, White wins.) This allows an opponent the chance to capture some of the offending stones on the turn after an incursion, or to counterattack on the opposite side of the board.

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