Grande Acedrex

How Grande Acedrex is played

Grande Acedrex is the great chess of Alfonso X’s Book of Games (1283): a board of twelve squares by twelve, with animals beside the king, the rooks and the pawns. The goal is to checkmate the opposing king: to attack it so that no move can save it. An attacked king is in check, and no move may leave your own king attacked.

The board and the start

The board has twelve files, a to l, and twelve ranks. On White’s first rank stand, from a1: rook, lion, unicorn, giraffe, crocodile, aanca, king (g1), crocodile, giraffe, unicorn, lion, rook; the twelve pawns stand on the fourth rank, and the ranks between are empty. Black stands the same way on the twelfth and ninth ranks, the kings facing each other on the g-file.

The pieces

The rook moves along ranks and files and the crocodile along the diagonals, as far as they like. The lion jumps three squares straight, or three one way and one the other; the giraffe jumps three squares one way and two the other. Both jump over whatever stands between. The aanca steps one square diagonally and may go on from there straight, away from where it came, as far as it likes; the unicorn jumps as a knight and may go on from there diagonally in the same direction. Neither may go on past a piece standing on that first square.

The king

The king steps one square in any direction. On its first move it may instead leap two squares, straight or diagonally, also over a piece, but only onto an empty square, not out of check and not across a square the opponent attacks.

Pawns

A pawn moves one square forward and captures one square diagonally forward; there is no double step and no en passant. On the last rank it becomes the piece that started on its file: a rook on the a- and l-files, a lion on b and k, a unicorn on c and j, a giraffe on d and i, a crocodile on e and h, an aanca on f and g.

The die

Alfonso had a die of eight faces made so that the game would go faster. With the die (a choice when you set up the game) every turn begins with a throw that names the kind of piece to move: 8 the king, 7 the aanca, 6 the unicorn, 5 the rook, 4 the lion, 3 the crocodile, 2 the giraffe, 1 a pawn. If no piece of that kind can move, the turn is lost. Checkmate and stalemate do not depend on the throw; a king left in check by a lost turn may be taken, and that wins.

Winning

Checkmate wins. A player who cannot move but is not in check is stalemated and has lost. A player left with the king alone loses as well, unless the king can take the opponent’s last piece at once: then the game is drawn.

Draws

The same position three times, or fifty moves each without a capture or a pawn move, is a draw. The book says nothing on stalemate, the bare king or draws: these rules are reconstructed from Alfonso’s ordinary chess and from what most modern sources give.

Other readings

The manuscript is unclear on several moves. H. J. R. Murray (1913) put the king on f1 and read the giraffe as a leap of four squares and one, the lion as a leap of three squares straight only, and the unicorn as a knight on its first move and a bishop afterwards. This app follows Jean-Louis Cazaux’s reconstruction, which most modern sources give and which keeps Alfonso’s own order of the pieces’ worth.

The story

Castile (Spain) · 1283, in King Alfonso X’s Book of Games

When and where

Grande Acedrex is the great chess of the Book of Games of King Alfonso X of Castile, finished in Seville in 1283. The manuscript calls it grant acedrex and says it was made in India, after the ancient kings who showed their power with armies and with strange birds and beasts.

How it changed

It made the board twelve squares by twelve, with twelve pieces and twelve pawns a side, and gave each new piece the ways of an animal: the crocodile strikes aslant, as it does in the Nile; the giraffe makes a sideways jump before it runs; the unicorn leaps like a horse before it charges; the lion leaps farther than any beast. Because the game was so slow, Alfonso had dice of eight faces made, one face for each kind of piece.

Today

No later medieval mention of the game is known. Its rules come from the manuscript alone, kept in the library of El Escorial, and its readers disagree on several moves. This app plays Jean-Louis Cazaux’s reconstruction, which most modern sources give.

Did you know?

The aanca is not a griffin, as it was long translated, but the roc of Arabic tales: the book says it is so big that it carries off the elephant to its nest. The book’s “unicorn”, two-horned and as large as an elephant, is a rhinoceros.

Original piece names

rey (king) · aanca (the roc, a giant bird) · unicornio (unicorn, a rhinoceros) · roque (rook) · leon (lion) · cocatriz (crocodile) · zaraffa (giraffe) · peon (pawn)

Sources: Libro de los juegos (1283) · H. J. R. Murray, A History of Chess (1913) · Wikipedia

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• Atomic chess · Every capture is an explosion that clears the pieces around it.
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• Racing Kings · No pawns, no checks: the first king on the far rank wins.
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• Dunsany’s chess · Lord Dunsany’s game of 1942: 32 pawns against a full army.
• Los Alamos chess · Chess on 6 × 6 without bishops, the first game a computer played (1956).
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• Fog of War · You only see where your pieces can move. Capture the king to win.
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• Shafran’s hexagonal chess · Hexagonal chess on 70 cells, with castling and pawns that step three.
• Spartan chess · Persians against Spartans: chess’ army against two kings and new pieces.
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Big chess

• Complete chess · The Arabic chess of the 9th century on 10 × 10, with two dabbābas a side.
• Courier chess · Medieval Germany’s chess on a 12 × 8 board, with the courier, the man and the schleich.
• Tamerlane chess · Timur’s great chess on an 11 × 10 board, with giraffes, camels and citadels.
• Carrera’s chess · The first chess on ten files, from a Sicilian priest’s book of 1617.
• Duke of Rutland’s chess · Fourteen files, with the concubine and two crowned rooks a side.
• Bird’s chess · Henry Bird’s ten-file chess of 1874, with the guard and the equerry.
• Capablanca chess · Ten files and two new pieces: the archbishop and the chancellor.
• Gothic chess · Ed Trice’s setup of 2000, today called Trice’s Chess.
• Capablanca Random · Capablanca chess from one of 12,118 shuffled starts.
• Embassy chess · Grand chess’ row of pieces on a 10 × 8 board.
• Janus chess · Two januses a side, each moving as a bishop or a knight.
• Grand chess · Christian Freeling’s 10 × 10 game: pawns promote only to lost pieces.
• S-chess · Chess with a hawk and an elephant in hand, placed as the back rank leaves.

The chess family

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• Byzantine chess · Shatranj on a round board: the rook circles, pawns never promote.
• Medieval chess · Europe’s chess before 1475: the ferz and the king may leap on their first move.
• Senterej · Ethiopian chess: no turns until the first capture, then Shatranj.
• Shatar · Mongolian chess: the bers, the camel, and a mate that needs a shak.
• Makruk · Thai chess: a slow, strategic game with a counting rule.
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• Malay chess · Chess of the Malay world: the king leaps, a crowned pawn walks back.
• Xiangqi · Chinese chess: a river, palaces and a cannon that jumps to capture.
• Minixiangqi · Xiangqi on 7 × 7 points: no river, no advisors, no elephants.
• Manchu chess · Red’s lone chariot moves as horse and cannon too, against a full army.
• Jieqi · Xiangqi with the pieces face down: each is revealed by its first move.
• Banqi · Xiangqi’s pieces face down on half a board: turn them up, take by rank.
• Janggi · Korean chess: no river, palace diagonals and a cannon that always jumps.
• Shogi · Japanese chess: captured pieces return to the board on your side.
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• Chu shogi · Japan’s great shogi on 12 × 12: no drops, and a lion that moves twice.
• Tori shogi · Bird shogi on 7 × 7: a phoenix, quails and swallows, with drops.

More players

• Chaturaji · India’s four-handed chess: kings can be captured, captures score.
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• Three-player chess · Three armies on a hexagonal board: you against two bots.
• Four-player chess · Four armies on a cross-shaped board: in teams or all against all.
• Bughouse · Two boards, two teams: what you capture goes to your partner's hand.
• Eight-player chess · Eight armies on a board of 516 squares: all against all, in pairs or four against four.
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