Editing Castling (section)

==History==
{{Chess diagram
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|  |xx|xo|  |kd|  |xo|xx
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| Castling under medieval rules. Symbol color corresponds to king color. Circles represent English, Spanish, French, and Lombardy movement; crosses represent Lombardy movement only.
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Castling has its roots in the ''king's leap''. There were two forms of the leap: the king would move once like a [[Knight (chess)|knight]], or the king would move two squares on its first move. The knight move might be used early in the game to get the king to safety or later in the game to escape a threat. This second form was [[Chess in Europe|played in Europe]] as early as the 13th century. In North Africa, the king was transferred to a safe square by a two-move procedure: the king moved to the player's second {{chessgloss|rank}}, and the rook and king moved to each other's original squares.<ref>{{harvcol|Davidson|1981|p=48}}</ref>

Various forms of castling were developed due to the spread of rulesets during the 15th and 16th centuries which increased the power of the [[queen (chess)|queen]] and [[bishop (chess)|bishop]], allowing these pieces to attack from a distance and from both sides of the board, thus increasing the importance of king safety.<ref>{{harvcol|Davidson|1981|p=16}}</ref>

The rule of castling has varied by location and time. In medieval England, Spain, and France, the white king was allowed to jump to c1, c2, d3, e3, f3, or g1<ref>c1, c2, c3, d3, e3, f3, g1, g2, or g3 according to [[H. J. R. Murray]]</ref> if no capture was made and the king was not in check and did not move over check; the black king might move analogously. In Lombardy, the white king might also jump to a2, b1, or h1, with corresponding squares applying to the black king. Later, in Germany and Italy, the rule was changed such that the king move was accompanied by a [[Pawn (chess)|pawn]] move.

In the [[Göttingen manuscript]] (c. 1500) and a game published by [[Luis Ramírez de Lucena]] in 1498, castling consisted of moving the rook and then moving the king on separate moves.

The current version of castling was established in France in 1620 and in England in 1640.<ref>{{harvcol|Sunnucks|1970|p=66}}</ref> It served to combine the rook's move and the king's jumping move into a single move.<ref>{{cite web |last1=McCrary |first1=John |title=The Evolution of Modern Chess Rules: Castling |url=https://new.uschess.org/news/evolution-modern-chess-rules-castling |website=US Chess Federation |date=18 May 2021 |access-date=13 June 2023}}</ref>

In Rome, from the early 17th century until the late 19th century, the rook might be placed on any square up to and including the king's square, and the king might be moved to any square on the other side of the rook. This was called ''free castling''.

In the 1811 edition of his chess treatise, [[Johann Baptist Allgaier|Johann Allgaier]] introduced the 0-0 notation. He differentiated between 0-0r (right) and 0-0l (left). The 0-0-0 notation for queenside castling was introduced in 1837 by [[Aaron Alexandre]].<ref>Stefan Bücker: "Was bedeutet 0-0?" (What does 0-0 mean?), in: ''[[Kaissiber]]'', No. 18, 2002, pp.70–71</ref> The practice was adopted in the first edition (1843) of the influential ''[[Handbuch des Schachspiels]]'' and soon became standard. In English [[descriptive notation]], the word "Castles" was originally spelled out, adding "K's R" or "Q's R" if disambiguation was needed; eventually, the 0-0 and 0-0-0 notation was borrowed from the algebraic system.