Ruy Lopez, Morphy Defence

The Ruy Lopez (; ), also called the Spanish Opening or Spanish Game, is a chess opening characterised by the moves:

:1. e4 e5
:2. Nf3 Nc6
:3. Bb5

The Ruy Lopez is named after 16th-century Spanish priest Ruy López de Segura. It is one of the most popular openings, with many variations. In the ''Encyclopaedia of Chess Openings'' (''ECO''), all codes from C60 to C99 are assigned to the Ruy Lopez.

History

The opening is named after the 16th-century Spanish priest Ruy López de Segura, who made a systematic study of this and other openings in the 150-page book on chess ''Libro del Ajedrez'', written in 1561. Although it bears his name, this particular opening was included in the Göttingen manuscript, which dates from c.1490. Popular use of the Ruy Lopez opening did not develop, however, until the mid-19th century, when the Russian theoretician Carl Jaenisch "rediscovered" its potential. The opening remains the most commonly used amongst the open games in master play; it has been adopted by almost all players during their careers, many of whom have played it with both colours. Due to the difficulty for Black in achieving equality, a common nickname for the opening is "The Spanish Torture".

Basics

At the most basic level, White's third move attacks the knight that defends the e5-pawn from the attack by the f3-knight. White's apparent threat to win Black's e-pawn with 4.Bxc6 dxc6 5.Nxe5 is illusory—Black can respond 5...Qd4, forking the knight and e4-pawn, winning back the with a good position. White's 3.Bb5 is still a good move, however; it a piece, prepares castling, and sets up a potential pin against Black's king. Since White's third move carries no immediate threat, Black can respond in a wide variety of ways.

Traditionally, White's objective in playing the Ruy Lopez is to spoil Black's pawn structure; either way Black recaptures following the exchange on c6 will have negative features, although recapturing gains the . In modern practice, however, White does not always exchange bishop for knight on c6, preferring the retreat 4.Ba4 if chased by 3...a6.

The theory of the Ruy Lopez is the most extensively developed of all Open Games, with some lines having been analysed well beyond move thirty. At nearly every move there are many reasonable alternatives, and most have been deeply explored. It is convenient to divide the possibilities into two groups based on whether or not Black responds with 3...a6, the Morphy Defence, named after Paul Morphy, although he was not the originator of the line. The variations with Black moves other than 3...a6 are older and generally simpler, but the Morphy Defence lines are more commonly played.

Morphy Defence: 3...a6

The most commonly played third move for Black is the Morphy Defence, 3...a6, a move which forces White to decide whether to retreat or to exchange for Black's knight. The Morphy Defence thus "puts the question" to the white bishop, a traditional usage which Larry Evans attributed to Aron Nimzowitsch. The main point of 3...a6 is that after the common retreat 4.Ba4, Black will have the possibility of breaking a future pin on the by playing ...b5. White must take some care not to fall into the Noah's Ark Trap, in which Black traps White's on the b3-square with a ...a6, ...b5, and ...c4 pawn advance on the .
Ercole del Rio, in his 1750 treatise ''Sopra il giuoco degli Scacchi, Osservazioni pratiche dell'anonimo Modenese'' (On the game of Chess, practical Observations by an anonymous Modenese), was the first author to mention 3...a6. The move became popular after it was played by Paul Morphy, however, and it is named for him. An influential chess player at that time, Wilhelm Steinitz, did not approve of the move, however; in 1889, he wrote, "on principle this ought to be disadvantageous as it drives the bishop where it wants to go". Steinitz's opinion did not prevail, however; today, 3...a6 is played in over 65 percent of all games beginning with the Ruy Lopez.

Morphy Defence: alternatives to Closed Defence

After 3...a6, the most commonly played line is the Closed Defence, which goes 4.Ba4 Nf6 5.0-0 Be7, discussed in the two following sections. Alternatives to the Closed Defence described in this section are:
* 4.Bxc6 (Exchange Variation)
* 4.Ba4
** 4...b5 5.Bb3 Na5 (Norwegian Defence)
** 4...b5 5.Bb3 Bc5 (Graz Defence)
** 4...b5 5.Bb3 Bb7 (Caro Variation)
** 4...Bc5 (Classical Defence Deferred)
** 4...Nge7 (Cozio Defence Deferred)
** 4...g6 (Fianchetto Defence Deferred)
** 4...f5 (Schliemann Defence Deferred)
** 4...d6 (Modern Steinitz Defence)
** 4...Nf6 5.Nc3 (Ruy Lopez Four Knights Variation)
** 4...Nf6 5.Qe2 (Wormald Attack)
** 4...Nf6 5.d4 (Mackenzie Variation)
** 4...Nf6 5.d3 (Anderssen Variation)
** 4...Nf6 5.0-0 d6 (Russian Defence)
** 4...Nf6 5.0-0 Bc5 (Møller Defence)
** 4...Nf6 5.0-0 b5 6.Bb3 Bb7 (Arkhangelsk Defence)
** 4...Nf6 5.0-0 b5 6.Bb3 Bc5 (Modern Arkhangelsk Defence)
** 4...Nf6 5.0-0 Nxe4 (Open Defence)

Exchange Variation: 4.Bxc6

In the Exchange Variation, 4.Bxc6, (''ECO'' C68–C69) White damages Black's pawn structure, giving them a ready-made long-term plan of playing d4 ...exd4 Qxd4, followed by exchanging all the pieces and winning the pure pawn ending. Max Euwe gives the pure pawn ending in this position (with all pieces except kings removed) as a win for White. Black gains good compensation in the form of the bishop pair, however, and the variation is not considered White's most ambitious, though former world champions Emanuel Lasker and Bobby Fischer employed it with success.

After 4.Bxc6, Black almost always responds 4...dxc6. The similar move 4...bxc6 is rarely played due to the reply 5.d4 exd4 6.Qxd4 which gives White control of the centre. After 4...dxc6, the obvious 5.Nxe5 is weak, since 5...Qd4 6.Nf3 Qxe4+ 7.Qe2 Qxe2+ 8.Kxe2 leaves White with no compensation for Black's bishop pair.

In the late 19th and early 20th centuries, Emanuel Lasker had great success with 5.d4 exd4 6.Qxd4 Qxd4 7.Nxd4, most notably his famous win against José Raúl Capablanca in the St. Petersburg 1914 chess tournament.

Since then, better defences for Black have been developed, and this line is considered to slightly favour Black. Jon Jacobs wrote in the July 2005 ''Chess Life'' (p. 21): "A database search (limited to games longer than 20 moves, both players FIDE 2300+) reveals the position after 7.Nxd4 was reached 20 times from 1985–2002. White's results were abysmal: +0−7=13."

After 5.Nc3, Black usually plays 5...f6 to defend the e-pawn. A notable game is Adhiban– Nakamura from the 2013 FIDE World Cup.

The flexible 5.0-0 is sometimes called the Barendregt Variation, but it was Fischer who developed it into a serious weapon in the 1960s. Unlike 5.d4, it forces Black to defend the e-pawn, usually with 5...f6, 5...Bg4, 5..