Pirc: 4.Bg5 Bg7

Pirc: 4.Bg5 Bg7

Definition

“Pirc: 4.Bg5 Bg7” refers to a branch of the Pirc Defence that arises after the moves 1. e4 d6 2.d4 Nf6 3.Nc3 g6 4.Bg5 Bg7. It is coded B07 in modern opening encyclopedias and is sometimes called the Byrne, Bayonet, or Classical Variation with an early bishop pin. The sequence begins with White pinning the f6-knight; Black calmly continues with …Bg7, completing the fianchetto and preparing to castle. From this tabiya, the struggle usually revolves around whether White can expand in the centre (e4-e5 or f2-f4) before Black strikes back with …c5 or …e5.

Move-order snapshot

Starting position after 4…Bg7 (White to move):

• White pieces: King e1, Queen d1, Rooks a1/h1, Knights c3, Bishops g5/c1, pawns on a-h files.
• Black pieces: King e8, Queen d8, Rooks a8/h8, Bishops g7/c8, Knight f6, pawns d6/g6, etc.

Strategic themes

• Pin & central tension: The bishop on g5 hampers Black’s natural …Nbd7 because the f6-knight is pinned. White hopes to push e4-e5 or f2-f4 under favourable circumstances.
• Black’s counterplay: Black typically answers with …c6 and …Qa5, or …a6 and …b5, undermining d4 and discouraging an early e5 thrust. The latent pawn break …e5 is another thematic equaliser.
• King-side versus queen-side play: If White castles long (O-O-O) and throws pawns on the kingside (h4, f4, g4), the game may resemble the Yugoslav Attack of the Dragon. Conversely, a quiet short-castling scheme can transpose into classical King’s-Indian-style manoeuvring.

Typical plans for White

1. Bolster the pin: Qd2, sometimes followed by Bh6 to trade the fianchetto bishop.
2. Space advance: f2-f4 → e4-e5, or e4-e5 immediately if Black allows.
3. Opposite-side castling attack: O-O-O, h2-h4-h5, opening files against the Black king.
4. Central build-up: Nf3, Bd3, Qe2, preparing long-term pressure on e5 and c4 squares.

Typical plans for Black

1. Rapid queenside expansion: …c6-b5-b4 striking at Nc3 and d4.
2. Timely pawn breaks: …e5 or …c5 challenging the centre directly.
3. Unpin & consolidate: …h6 followed by …g5 or …Nbd7 when tactically feasible; sometimes …Nbd7 is played at once if 5.Qd2 is omitted.
4. Piece pressure: …Qa5 or …Qb6 double-hitting g5 and d4, forcing White to clarify his intentions.

Historical development & notable games

The line became fashionable in the late 1960s after American GM Robert Byrne scored several wins with it, inspiring the “Byrne System” moniker. At elite level it sporadically surfaced—most famously in the blitz game Fischer vs Petrosian, Herceg Novi 1970, where Fischer’s 4.Bg5 set the stage for a whirlwind kingside assault. Although modern engines show Black has adequate resources, the variation remains popular in club play because of its rich tactical potential.

Illustrative miniature

Byrne-R. Wade, Palma de Mallorca 1969 (annotated excerpt):

White’s aggressive set-up with Qd2, f4-f5 and O-O-O led to sharp complications in which his initiative proved decisive.

Interesting facts & anecdotes

• Because 4.Bg5 often transposes to King’s Indian Defence territory via reversed colours, some authors dub it the “Anti-KID Pirc.”
• Grandmaster John Nunn once joked that the line is “an instant headache for Pirc players who neglect their theory for a week.”
• In online bullet, 4.Bg5 scores disproportionately well because the tactical motifs (e5 breaks, sacrifices on f6, or Bh6 ideas) are easy to execute quickly.
• The leading database move after 4.Bg5 is indeed 4…Bg7, but adventurous Black players have experimented with 4…Nbd7!? and even 4…c6!? immediately attempting to sidestep heavy theory.

Summary

The Pirc line with 4.Bg5 Bg7 is an enterprising choice in which White grabs space and pins a key defender; Black, meanwhile, trusts in the flexibility of the Pirc structure to undermine the centre at a moment of his choosing. Rich in imbalance and dynamic play, it offers fertile ground for creative middlegame battles and remains a staple weapon in many attacking repertoires.