a	b	c	d	e	f	g	h	i	j	k	l
12													12
11													11
10													10
9													9
8													8
7													7
6													6
5													5
4													4
3													3
2													2
1													1
	a	b	c	d	e	f	g	h	i	j	k	l

Grant Acedrex starting position. From left to right, back rank pieces are: rook, lion, unicornio, giraffe, crocodile, aanca, king, crocodile, giraffe, unicornio, lion, rook.

Grant Acedrex is a medievalchess variant dating back to the time of KingAlfonso X of Castile. It appears in theLibro de los Juegos of 1283.

The following rules are from the reconstruction given on the website of Jean-Louis Cazaux, based on work by him and Sonja Musser. The game is played on a 12×12 board.

Theking moves as like modern king. ItsBetza notation is thusK.Castling does not exist inGrant Acedrex. However, on its first move, a king may make a diagonal or orthogonal leap of two squares (Betza notationAD) in addition to its normal moves.

Theaanca (a beautiful and fearsome bird, very similar to aroc, sometimes translated incorrectly asgryphon) moves one square diagonally (like aferz), before optionally continuing orthogonally outward any number of squares. Its Betza notation ist[FR].

	a	b	c	d	e	f	g	h	i	j	k	l
12													12
11													11
10													10
9													9
8													8
7													7
6													6
5													5
4													4
3													3
2													2
1													1
	a	b	c	d	e	f	g	h	i	j	k	l

Move of the aanca

Theunicornio (the illustration on the medieval codex shows a rhinoceros's head) moves like a modernknight, before continuing diagonally outward any number of squares. (InH. J. R. Murray's translation, its first move is a non-capturing knight move, after which it acts as a bishop for the rest of the game.) Its Betza notation ist[NB].

	a	b	c	d	e	f	g	h	i	j	k	l
12													12
11													11
10													10
9													9
8													8
7													7
6													6
5													5
4													4
3													3
2													2
1													1
	a	b	c	d	e	f	g	h	i	j	k	l

Move of the unicornio

• Thelion moves like athreeleaper or acamel, and can jump (a combined (3,0)-leaper and (3,1)-leaper). (In Murray's translation, it can only move as a threeleaper.) Its Betza notation isHC.

	a	b	c	d	e	f	g	h	i	j	k	l
12													12
11													11
10													10
9													9
8													8
7													7
6													6
5													5
4													4
3													3
2													2
1													1
	a	b	c	d	e	f	g	h	i	j	k	l

Move of the lion

• Thegiraffe moves like azebra, a (3,2)-leaper. (In Murray's translation, it is a (4,1)-leaper.) Its Betza notation isZ.

	a	b	c	d	e	f	g	h	i	j	k	l
12													12
11													11
10													10
9													9
8													8
7													7
6													6
5													5
4													4
3													3
2													2
1													1
	a	b	c	d	e	f	g	h	i	j	k	l

Move of the giraffe

• Thecrocodile moves like the modernbishop. Its Betza notation isB.

• Therook moves like the modern rook. ItsBetza notation isR.

• Thepawn moves like the modern pawn, but cannot make an initial double step or captureen passant. Its Betza notation ismfWcfF. When it reaches the other end of the board (the twelfth rank for White, or the first rank for Black), it promotes to the piece that was originally there: the exception is that a pawn promoting on the g-file becomes an aanca. For example, a pawn promoting on the a-file would become a rook.

In Grant Acedrex, a player wins by eithercheckmating orstalemating the opponent. A player can also win by capturing all the opponent's pieces leaving them with abare king.

The game could be sped up by using eight-sided dice to dictate which piece could move that turn, ranking them in the order: king (8), aanca (7), unicornio (6), rook (5), lion (4), crocodile (3), giraffe (2), and pawn (1).^[1]

The multi-variantChess enginesFairy-Max and Postduif can play Grant Acedrex under theXBoard orWinBoard user interface.^[2][3][4]

Bibliography

• Cazaux, Jean-Louis; Knowlton, Rick (2017).A World of Chess, Its Development and Variations through Centuries and Civilizations. McFarland.ISBN 978-0-7864-9427-9.
• Gollon, John (1973).Chess Variations: Ancient, Regional, and Modern.Charles E. Tuttle Company Inc.ISBN 0-8048-1122-9.
• Pritchard, D. B. (1994).The Encyclopedia of Chess Variants. Games & Puzzles Publications.ISBN 0-9524142-0-1.
• Pritchard, D. B. (2007). Beasley, John (ed.).The Classified Encyclopedia of Chess Variants. John Beasley.ISBN 978-0-9555168-0-1.

• Los libros de acedrex dados e tablas: Historical, artistic and metaphyisical dimensions of Alfonso X’sBook of Games (PDF), Sonja Musser Golladay, PhD dissertation, University of Arizona, 2007
• Grant Acedrex by Jean-Louis Cazaux
• Grant Acedrex atThe Chess Variant Pages

• Games related to chaturanga
• Abstract strategy games
• History of chess
• Medieval chess
• 13th century in Castile

• Articles with short description
• Short description is different from Wikidata