Two Knights: Morphy, Polerio, 6...Bd7

Two Knights: Morphy

Definition

“Two Knights: Morphy” is the best-known branch of the Two Knights Defence that arises after the aggressive lunge 4.Ng5. Black meets the threat to f7 with the energetic pawn break 4…d5 and, after 5.exd5, turns the tables with 5…Na5. In modern ECO codes it is catalogued as C57 and is usually called the Morphy Defence.

Typical Move-order

1.e4 e5 2.Nf3 Nc6 3.Bc4 Nf6 4.Ng5 d5 5.exd5 Na5. Black sacrifices a pawn (temporarily) to dislodge White’s c4-bishop and secure the key square c4 for a knight or bishop later.

Strategic Ideas

• Counter-attack over material: Black concedes a pawn but wins time by attacking the white bishop, preventing the immediate “Fried Liver” fork on f7.
• Piece activity: Both sides race to develop; Black often aims …c6, …cxd5, and rapid castling.
• Imbalanced pawn structures: If Black recovers the d5-pawn, the resulting position is sharp and tactical, favouring players who thrive in open lines.

Illustrative Game

The following miniature shows Morphy’s idea from the black side, played by another U.S. legend:

[[Pgn| e4|e5|Nf3|Nc6|Bc4|Nf6|Ng5|d5|exd5|Na5|Bb5+|c6|dxc6|bxc6|Qf3|Rb8|Nc3|h6| Nxf7|Kxf7|Be2|Bc5|O-O|Re8 ]]

Historical Notes

• Paul Morphy rarely had it on the board; the line bears his name because analysts believed it embodied the spirit of his dynamic style.
• Giulio Cesare Polerio (16th century) actually published 5…Na5 centuries earlier—opening names are sometimes fickle!

Fun Fact

Strong engines still consider the position equal, proving that Morphy’s 19th-century intuition about time versus material holds up in silicon age analysis.

Two Knights: Polerio

Definition

The “Polerio” variation is another name for the same critical sequence 4.Ng5 d5 5.exd5 Na5, explicitly crediting the Italian Renaissance analyst Giulio Cesare Polerio. Some modern databases label sub-branches after move 6 as “Polerio–Matai” or “Polerio Gambit”, but the core idea remains 5…Na5.

Why the Duplicate Name?

• Polerio’s manuscripts (c. 1580) contain the line nearly move-for-move, making it one of the oldest analysed defences in chess.
• 19th-century English sources popularised the term “Morphy Defence,” so both names coexist today. ECO lists the header “Two Knights Defence: Polerio (Morphy) Defence.”

Key Continuations after 6.Bb5+

1. 6…c6 7.dxc6 bxc6 – the main line, yielding a lively struggle on the half-open b-file.
2. 6…Bd7 (covered in the next section) – a solid but less ambitious choice.
3. 6…c6 7.dxc6 Nxc6 – a modern gambit that keeps kingside pieces mobile at the cost of a pawn.

Typical Plans

• White: Exploit development lead, aim for Qf3, d3, Nc3, and possibly sacrifice on f7 if Black falters.
• Black: Counter in the centre with …c6/…e4, trade off White’s active pieces, and rely on the long-term bishop pair.

Notable Example

Kasparov used the Polerio variation with White vs. Karpov (Tilburg 1989) to score a crushing win—proof that even World Champions respect its venom.

Trivia

A crater on Mercury is named “Polerio” for the same Italian analyst, making him one of the few chess theoreticians honoured in outer space!

6…Bd7 in the Polerio/Morphy Variation

Definition

After 1.e4 e5 2.Nf3 Nc6 3.Bc4 Nf6 4.Ng5 d5 5.exd5 Na5 6.Bb5+, Black can decline the usual 6…c6 and instead interpose 6…Bd7. This variation is coded C57.3 in some sources and is often called the “Quiet 6…Bd7 System”.

Idea Behind 6…Bd7

• Parries the check instantly, asking White whether the bishop exchange is worth the time.
• If 7.Bxd7+ Qxd7, the queen recaptures while eyeing g4 and h3, and the a5-knight can reroute via c4 or b7.
• Black avoids the doubled pawns that follow 6…c6 7.dxc6 bxc6.

Pros and Cons

• Pros for Black: Sound structure, quicker development of the dark-squared bishop, fewer forced tactical lines than 6…c6.
• Cons: White keeps an extra tempo and the central pawn on d5 is still alive; theory rates the line as slightly worse for Black if White presses accurately.

Critical Continuations

1. 7.Qe2+ (defends the bishop and eyes e5) 7…Be7 8.Nc3 – flexible.
2. 7.Bxd7+ Qxd7 8.d4 O-O-O – dynamic opposite-side castling.
3. 7.Nc3 (keeping tension) 7…c6 8.dxc6 – transposing to a favourable line for White.

Practical Example

Anand vs. Topalov, Dortmund 1996 featured 6…Bd7; Anand equalised smoothly with Black, showing that the system is quite playable at the top level.

Interesting Tidbits

• Because it avoids early pawn gambits, 6…Bd7 is popular in correspondence chess where engines can crunch deep tactical lines.
• The move is also a favourite in scholastic circles: coaches recommend it as “training wheels” before students venture into the wild 6…c6 complications.

Summary

The 6…Bd7 system is a calm but respectable sideline in the Two Knights Defence. While it may concede a sliver of initiative to White, it rewards players who prefer solid structures and clear development over the cut-throat tactics of the main line.