Elizabeth Nash, in the London Independent (March 2, 2004):

ISABELLA, QUEEN of Castile, the monarch who unified Spain and sent Christopher Columbus to discover America, was also the inspiration for the figure of the queen in modern chess.

The Arabs brought chess to Spain when they invaded it in the eighth century, but it was not until the late fifteenth century, when Queen Isabella was at the height of her powers, that the queen become the most powerful piece, according to research by chess historians.

"In its original form, the equivalent of the queen was male, a piece known in Spanish as alferza, from the Persian, meaning something like vizier or adjutant," said Govert Westerveld, a Dutch chess historian and former youth champion who lives in Spain.

"The figure was weak, and its movements limited. Later, around 1475, when Isabella was crowned queen of Castile, the figure became female but able to move only one square at a time, like the king. Not until 1495, when Isabella was the most powerful woman in Europe, were the present rules of chess established, in which the queen roams freely in all directions on the board," Dr Westerveld said yesterday.

Chess has always reflected the real world, says Dr Westerveld, who presented his book on the evolution of modern chess in Valencia last week.

It was, he said, no accident that the appearance of the first female chess piece, bearing a crown, sword and sceptre, coincided with the emergence of Queen Isabella, who astonished Europe with her powers of leadership, bravery and determination.

The game of chess represents a battle, a confrontation between two armies, in which the king is flanked by his castles, his bishops (originally elephants) and his cavalry, while the ranks of pawns represent the peasants or footsoldiers in the front line. The game was hugely popular throughout al-Andalus, as Moorish Spain was known, and reflected the constant clashes between rival Arab kingdoms, and between Christian warrior knights and the occupying "infidels".

The theory goes that these real-life warriors found the pace of chess too slow, so the queen was given more freedom of movement, combining the powers of the castle and the bishop. This loosened up the opening moves, gave more variety to the middle game and transformed the endgame by enabling a pawn to become queen on the final square. All this hastened the moment of checkmate, when "the king dies".

Jose Antonio Garzon, a Valencian historian who works with Dr Westerveld, said a Valencian poem called "Lovers' Chess", written in 1475, the year of Isabella's coronation, described for the first time the present day moves of the queen on the chessboard. The work is an allegory that describes a complete game of chess, and includes explicit allusions to the royal court of the time.