Sicilian Defence

1...c5 is the Sicilian defence, a counter-attacking, asymmetric opening. Black controls the d4 square with a flank pawn, asserting that trading their flank c-pawn for White's d-pawn will surely be to their advantage, as it will leave them with two central pawns to White's one. Black would love to one day achieve d5, and exploit the c-file should it open.

The main approach for White is the Open Sicilian: 2. Nf3 intending to bust open the position with 3. d4. This is the most testing approach, but as it is also normally what Black is most prepared for, a number of other approaches, the "anti-Sicilians", are also popular.

The drawback of 1...c5 is that it does not help Black to develop (compare 1...e5, which both controls d4 and opens a line for the king's bishop). After 1...c5, Black must eventually play another pawn move before a bishop can come out. Therefore White will be able to develop faster, and the most principled way to press this advantage is to open the position.

2. Nf3 is the Open Sicilian. This prepares 3. d4 cxd4 and White can recapture with the knight. They will have a centralised knight, clear lines to develop both bishops and their queen, and an open, attacking position. Black has a centre pawn majority and a half-open c-file. After the moves 2...Nc6 or 2...d6, White has the alternative 3. Bb5, the Rossolimo or Moscow variation.

White can also play 2. d4 immediately, without preparing it with 2. Nf3. After 2...cxd4 3. Qxd4!? would lose time to 3...Nc6. Instead, White may play 3. c3, the Smith-Morra gambit, to offer a pawn in exchange for faster development.

2. Nc3 is the chief alternative second move. White opts to avoid trading their d-pawn and keep the position closed. In the mainline Closed Sicilian, White fianchetttos their kingside bishop and plays d3, Be3, Nge2, and Qd2. This typically leads to a more closed and slow-burning position.

Another approach for White is to take advantage of their space on the kingside and launch the violent Grand Prix attack, where White plays an early f4, places their knight on f3 behind the pawn, and brings their queen into the attack via a Qd1-Qe1-Qh4 manoeuvre.

2. Nc3 is also a waiting move: after they get a bit more information about how Black wishes to play, White may still play Nf3 and d4 and transpose.

White may wish to put a pawn on d4 and have some hope of keeping it there.

2. c3, the Alapin, prepares to play 3. d4 and if the d-pawn is captured, to replace it with the c-pawn. This diffuses any advantage Black would hope to gain from trading a flank pawn for a centre pawn as White keeps two pawns in the centre.

Black can't prevent White from playing 3. d4 but they can at least ensure that White does not get to keep a big, classical centre with both d- and e-pawns side-by-side. The main moves are 2...Nf6, inducing 3. e5 Nd5 4. d4, or 2...d5, taking advantage of the fact that after 3. exd5 Qxd5 White's c3 pawn prevents Nc3 to kick the queen.

Alternatively, White can try to reduce Black's control of the d4 square, then play d4.

If White likes Black's idea of trading a more peripheral pawn for a less peripheral pawn, they can try to trade their b-pawn for Black's c-pawn. 2. b4, the Wing Gambit, tempts Black's c5 pawn away from controlling d4: after 2...cxb4 White can happily play d4 and achieve a two pawn centre. White solved one problem but now must contend with another: how to develop their knight, whose normal space c3 is now controlled by Black's pawn.

A more recent idea is 2. a3, the Mengarini variation, preparing 3. b4: after 2...Nc6 3. b4 cxb4 4. axb4 Nxb4 5. d4 White gets two pawns in the centre and no obstacle to developing their knight. If Black is less accommodating however, they will not take: 2...g6 3. b4 Bg7 (threatening Bxa1) 4. Nc3 d6 is the mainline.

2. f4, the MacDonnell attack, a violent attacking move like an accelerated Grand Prix attack. However, since White hasn't played Nc3 yet to control d5, Black has the option of 2...d5!, the Tal gambit. 2. f4 was the approach taken by MacDonnell against La Bourdonnais in 1834. The more usual approach to the Grand Prix today is to begin with 2. Nc3.

2. c4 is the Staunton-Cochrane variation. White locks down on the d5 square to prevent the freeing move ...d5 (a Maróczy bind), however the pawn move is committal and White has permanently weakened the d3 and d4 squares. This can transpose into a Botvinnik system otherwise seen in the Symmetrical English (where White puts pawns on c4, d3, e4, and g3 and plays Nc3, Ne3, and Bg2).

2. Bc4 is the Bowdler attack. The c4 square is less optimal for the bishop in this position than after 1. e4 e5 as Black is able to play 2...e6 to end its pressure on f7. ...d5 will soon follow and Black is thought to have the edge.

2. Ne2 is the Keres variation, a modest developing move which keeps White's options open. This is very transpositional; it is also played in the order 2. Nc3 & 3. Ne2 where it is called the Chameleon. White can later play d4 & Nxd4 to open up the position, by which time they may have move-ordered Black out of the Sicilian they usually play, or they can play a Closed Sicilian with g3 and Bg2.

2. Be2 can lead to positions where White plays in a compact, defensive way, prioritising castling before making any commitments on the queenside. White keeps the position closed, plays an early f4, Nf3, and castles. Not having played Nc3 yet they may play Nd2 and c3.

2. g3, preparing the fianchetto, is the Lasker–Dunne attack. This can transpose into a Closed Sicilian or White can combine it with c3 and d4. However this does allow Black the sequence 2...d5 3. exd5 Qxd5 (threatening Qxh8) 4. Nf3 to open the position.

2. e6?!, the so-called Pawn-push variation, seeks to take advantage of the fact that Black hasn't played ...e5. From e5, White's pawn will cramp Black's position and hamper development of their king's knight. However, Black can usually end up winning the pawn or trading it for development. Black is better after 2...Nc6 (attacking pawn and controlling d4) 3. Nf3 (defending pawn) Qc7 (attacking pawn) 4. Qe2 (defending pawn) f6! 5. exf6 Nxf6.

2. Qg4? is the delirious Amazon attack. White develops their queen out of order, only to allow Black to play ...Nf6 with tempo.

2. Ke2? is the worst possible move in the position. Though never played seriously it has for whatever reason a name, King David's Opening, perhaps to evoke David sallying forth to battle Goliath in single combat.

The earliest analysis of 1...c5 comes from a 1594 codex by Giulio Polerio l'Apruzzese (c. 1555-1610). It was analysed by Pietro Carrera in his 1617 work Il Gioco degli Scacchi (The Game of Chess). Carrera was born in Sicily so it is believed to be for him that the name Sicilian defence was adopted.^[1]

It was not originally considered to be a good opening for Black until it was used by La Bourdonnais in his 1834 match series against Alexander MacDonnell, a precursor to the modern world chess championship. La Bourdonnais's success led to a critical reappraisal: a few years later in 1842, Jaenisch wrote that 1...c5 was the best reply to 1. e4.^[1]

Andersen and Paulsen made major contributions to the theory in the 19th century, and by the early 20th century the Sicilian had entered the mainstream.^[1] With the discovery of new attacking ideas, it became Black's most feared weapon by the 1950s and is, pound for pound, the most exhaustively analysed of all openings.

Databases give White approximately 36% winning chances, drawing is at 30%, and Black wins 33%.

Estimated next move popularity: Nf3 74%, Nc3 10%, c3 7%, d4 3%, Bc4 2%, f4 2%, d3 1%, b3 1%, c4 1%, Ne2 1%, g3 0.4%, b4 0.4%, other moves less than 0.3%.

Note that these move frequencies are biased toward databases of stronger players. The next move frequency may be very different for club players. For instance, see the data from the Lichess database below where 2. Nf3 occurs less commonly at only 56% of the time while 2. Bc4 occurs as often as 7% of the time.

1. e4 c5

For explanation of theory tables, see theory table and for notation, see algebraic notation.

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Wikipedia has related information at Sicilian Defence

• Nunn's Chess Openings. 1999. John Nunn (Editor), Graham Burgess, John Emms, Joe Gallagher. ISBN 1-8574-4221-0.

• Modern Chess Openings: MCO-14. 1999. Nick de Firmian, Walter Korn. ISBN 0-8129-3084-3.

• Kasparov, Garry, & Keene, Raymond 1989 Batsford chess openings 2. ISBN 0-8050-3409-9.

• 365Chess: 1. e4 c5