The Trompowsky Attack begins with the bishop move ♗g5 on the second move, after d4 and ... ♞f6. White develops the dark-squared bishop before playing e3, exactly as in the London System (here), but in this opening the bishop attacks the knight and prepares to double Black's pawns.
1. d4 ♞f6 2. ♗g5
The threat is ♗xf6, and after a recapture with the g-pawn the black kingside pawn structure is damaged. This is not a lethal threat, because Black can allow it, but it forces Black to decide on a structure immediately.
The main attractions of the system are:
The price is also clear: White moves the bishop early, and the b2-pawn is often left without protection, so tempo-gaining moves such as ... ♛b6 or ... ♛a5+ appear in many lines. White must not play the moves automatically.
The most common reply is 2... ♞e4. Black violates the principle of not moving the same piece twice, but attacks the bishop and forces White to decide where it belongs.
1. d4 ♞f6 2. ♗g5 ♞e4
White has three main answers:
The move 3. ♘f3? is a mistake: after 3... ♞xg5 4. ♘xg5 e5 Black regains the time with a discovered attack, White's center is liquidated, and White has no compensation for the bishop pair.
White's bishop retreats to the active square. Black then has two main ideas, ... c5 and ... d5. The move f3 will chase the knight, but it also takes the best square away from White's own g1-knight.
1. d4 ♞f6 2. ♗g5 ♞e4 3. ♗f4 c5 4. f3 ♛a5+ 5. c3 ♞f6 6. d5 ♛b6 7. ♗c1 e6 8. c4 exd5 9. cxd5 c4 10. e3 ♝c5
Black's knight has moved three times, Black's queen twice, and White's bishop has returned to its starting square. White's bishop goes back to c1 to protect b2 against the queen on b6, and White has gained a space advantage in the center. The king often finds shelter on f2, defending the e3-pawn, which is an unusual but practical setup.
White can also open the position with 6. dxc5 ♛xc5 instead of 6. d5, which leads to a more balanced position.
The other main idea for Black is to build the center with ... d5. Here the b2-pawn becomes the focus point:
1. d4 ♞f6 2. ♗g5 ♞e4 3. ♗f4 d5 4. e3 c5 5. ♗d3 ♛b6 6. ♗xe4 dxe4 7. ♘c3
The natural ways of defending the pawn are inferior. 6. b3 creates weaknesses on the long diagonal, and 6. ♕c1 allows 6... cxd4 with a good game for Black. The correct reaction is 6. ♗xe4, removing the strong knight. After 6... dxe4 7. ♘c3 White develops quickly with pressure on the e4-pawn and the center, and Black's greedy 7... ♛xb2?! allows White to develop with tempo, for example with 8. ♘ge2.
The retreat 3. ♗h4 keeps the bishop on the diagonal, but it allows ... g5:
1. d4 ♞f6 2. ♗g5 ♞e4 3. ♗h4 g5 4. f3 gxh4 5. fxe4 c5
Material is equal: White has traded a bishop for a knight, and Black has a doubled h-pawn. The position is sharp and imbalanced, with a broad white center against the open g-file and the loose pawn on h4.
The variation 3. h4 defends the bishop in another way. If Black takes it with 3... ♞xg5, 4. hxg5 opens the h-file for the rook and gives White a comfortable game. Black should therefore respond by kicking the bishop instead:
1. d4 ♞f6 2. ♗g5 ♞e4 3. h4 h6 4. ♗f4 d5
Another common idea is 3... c5, met by 4. dxc5 ♞a6 5. ♘d2. This line could be a surprise weapon, but it costs a tempo on the rook pawn, so White should know why the move is played.
Black can ignore the threat and take the center with 2... d5. White can inflict doubled pawns at once:
1. d4 ♞f6 2. ♗g5 d5 3. ♗xf6 exf6 4. e3 ♝d6 5. c4 dxc4 6. ♗xc4 O-O 7. ♘c3 f5 8. ♘f3 ♞d7 9. ♕c2 c6 10. O-O ♞f6
Black usually recaptures with the e-pawn, which keeps a defensible structure and opens diagonals for the queen and the dark-squared bishop. The doubled f-pawns are not a serious weakness here, because they control the center and give Black active piece play. White has wasted a tempo by moving the bishop twice, and Black has the bishop pair, so White should not expect an opening advantage.
There is a trap in this line. In the diagram after 9... c6, the natural 10. ♕xf5? loses material to 10... ♞e5!, so White must castle or continue with 10. a4.
White has other options at move three:
The move 2... c5 invites White to take on f6, but also attacks the d4-pawn. White has two main choices. The first is to advance the pawn and accept a fight:
1. d4 ♞f6 2. ♗g5 c5 3. d5 ♛b6 4. ♘c3 ♛xb2 5. ♗d2 ♛b6 6. e4
This is the poisoned pawn variation. Black wins the pawn on b2, but the queen has to retreat, and White gains time for the central advance and development. White's compensation is a lead in development and a strong center, but it requires accurate play, because after 5. ♗xf6?! gxf6 6. Kd2 White's king becomes exposed.
The second choice is to take on f6 and then protect the pawn:
1. d4 ♞f6 2. ♗g5 c5 3. ♗xf6 gxf6 4. d5 ♛b6 5. ♕c1
The queen defends b2 and keeps the position balanced. Black has the bishop pair and the half-open g-file, and the structure is roughly equal. Here 5. ♘c3? would be a mistake, because 5... ♛xb2 wins the pawn under better circumstances for Black.
Black can also meet 4. dxc5 with 4... e6 or 4... ♛a5+ and reach comfortable positions, so the advance d5 is the more testing choice for White.
The move 2... e6 avoids doubled pawns, because the queen can recapture on f6, and it opens the diagonal for the king's bishop. The drawback is that the knight is pinned, and White can take more of the center:
1. d4 ♞f6 2. ♗g5 e6 3. e4 h6 4. ♗xf6 ♛xf6 5. ♘c3 ♝b4 6. ♕d2
After 3... h6 White can take the knight, because the recapture with the queen is safe. White obtains a broad center, while Black obtains the bishop pair and counterplay with ... c5 and ... ♞c6. The position is balanced, and the queen on f6 can become a target for tempo moves.
White has a quieter alternative in 3. ♘d2, which keeps the option of e4 and c3. After 3... h6 4. ♗h4 White keeps the bishop, and Black can continue with 4... d5 or 4... ♝e7.
The move 2... g6 prepares to fianchetto the bishop. If White takes at once with 3. ♗xf6, Black must recapture with the e-pawn, so White has an easy alternative, which keeps the tension:
1. d4 ♞f6 2. ♗g5 g6 3. ♘d2 ♝g7 4. e4
White builds a broad center with the knight on d2 and prepares to develop the other knight. This is a natural move that avoids exchanging the bishop for the knight at the wrong moment.
2... c6 threatens ... ♛b6, but it contains a trap for White. The automatic development move loses immediately:
1. d4 ♞f6 2. ♗g5 c6 3. e3 ♛a5+ 4. c3 ♛xg5
The move 3. e3?? blocks the bishop's retreat, so 3... ♛a5+ wins it with a double attack. White has to choose 3. ♗xf6 or 3. ♘f3 instead.
White can also play the bishop move after 1. d4 d5. It transposes to the Trompowsky if Black plays 2... ♞f6.