The French Defence is a chess opening characterised by the moves:
1. e4 e6
This is most commonly followed by 2.d4 d5. Black usually plays ...c5 soon after, attacking White's and gaining on the . The French has a reputation for solidity and resilience, although some lines such as the Winawer Variation can lead to complications. Black's position is often somewhat in the early game; in particular, the pawn on e6 can impede the of the bishop on c8.
Basics
Following the opening moves 1.e4 e6, the main line of the French Defence continues 2.d4 d5 (see below for alternatives). White sets up a , which Black immediately challenges by attacking the pawn on e4. The same position can be reached by transposition from a Queen's Pawn Game after 1.d4 e6 2.e4 d5 or the declining of a Blackmar–Diemer Gambit after 1.d4 d5 2.e4 e6.
White's options include defending the e4-pawn with 3.Nc3 or 3.Nd2, advancing it with 3.e5, or exchanging it with 3.exd5, each of which leads to different types of positions. Defending the pawn with 3.Bd3 allows 3...dxe4 4.Bxe4 Nf6, when Black gains either a tempo or the advantage of .
General themes
The diagram shows a pawn structure commonly found in the French. Black has more space on the queenside, so tends to focus on that side of the board, almost always playing ...c7–c5 early on to attack White's pawn chain at its base, and may follow up by advancing the a- and b-pawns.
Alternatively or simultaneously, Black will play against White's centre, which is cramping Black's position. In the unlikely case that the flank attack ...c7–c5 is insufficient to achieve counterplay, Black can also try ...f7–f6. In many positions, White may support the pawn on e5 by playing f2–f4, with ideas of f4–f5, but the primary drawback to the advance of the f-pawn is opening of the g1–a7 diagonal, which is particularly significant due to the black queen's oft-found position on b6 and the heavy pressure on d4. In addition, many French Advance lines do not provide White with the time to play f2–f4 as it does not support the heavily pressured d4-pawn. For instance, 1.e4 e6 2.d4 d5 3.e5 c5 4.c3 Nc6 5.f4? (if White plays Nf3, f4 will come much slower) 5...Qb6 6.Nf3 Nh6! and the knight will go to f5 to place fatal pressure on d4 and dxc5 will never be an option as the white king would be stuck in the centre of the board after ...Bxc5.
White usually tries to exploit the extra space on the , often playing for a mating attack. White tries to do this in the Alekhine–Chatard Attack, for example. Another example is the following line of the Classical French: 1.e4 e6 2.d4 d5 3.Nc3 Nf6 4.Bg5 Be7 5.e5 Nfd7 6.Bxe7 Qxe7 7.f4 0-0 8.Nf3 c5 9.Bd3 (). White's eyes the weak h7-pawn, which is usually defended by a knight on f6, but here it has been pushed away by e5. If 9...cxd4 (Black does better with 9...f5 or 9...f6), White can play the Greek gift sacrifice 10.Bxh7+ Kxh7 11.Ng5+ Qxg5 12.fxg5 dxc3 13.Qh5+! where Black has three minor pieces for the queen, a slight material superiority, but has a vulnerable king and White has good attacking chances.
Apart from a piece attack, White may play for the advance of the kingside pawns (an especially common idea in the endgame), which usually involves f2–f4, g2–g4 and then f4–f5 to use the spatial advantage on that side of the board. A white pawn on f5 can be very strong as it may threaten to capture on e6 or advance to f6. Sometimes the h-pawn to h5 or h6 may also be effective. A modern idea is for White to gain space on the queenside by playing a2–a3 and b2–b4. If implemented successfully, this will further restrict Black's pieces.
One of the drawbacks of the French Defence for Black is the , which is blocked in by the pawn on e6 and can remain passive throughout the game. An often-cited example of the potential weakness of this bishop is S. Tarrasch–R. Teichmann, San Sebastián 1912, in which the diagrammed position was reached after fifteen moves of a Classical French.