Chess Opening Theory/1. e4/1...e5/2. Nf3/2...Nc6/3. Bb5/3...Qf6

The move 3...Qf6!? is a rare and provocative sideline in the Ruy Lopez. Ignoring conventional wisdom, Black develops their queen early.

3...Qf6 aids in the defense of the e5 pawn as well as the knight on c6. Further, the queen adds a piece to the control of d4 and looks to potentially start a future kingside attack. If White delays castling, the queen can route to g6 (typically in response to Nc3 to Nd5) and pressure the undefended g2 pawn.

Black's plan typically includes developing Bc5 and Ne7 with d6 or d5. While the king knight is denied its usual post on f6, from e7 it can control d5, preventing White from easily playing Nd5 and also nullifies White's threat of trading off the knight on c6 and damaging Black's pawn structure.

White's plans are, as usual in the Ruy Lopez, to castle quickly and take over the center with c3 and d4 pawn pushes.

4. c3 readies a d4 advance. Black can respond with d6, a6, or g5 aiming to advance to g4 and displace White's knight.^[1] 4...Bc5 attempting to hold d4 fails to 5. d4 exd4 6. e5! driving Black's queen away and giving white a strong center.

4. O-O may be met by 4...Bc5 5. c3 Nge7. On e7, the knight is ready to capture back if Bxc6 and therefore keep control of the center.

4. Nc3 develops a piece with an aim to play Nd5, displacing the black queen and potentially hindering Black's development and/or defense of e5.

3...Qf6 has no official name in the Encyclopedia of Chess Openings (ECO). The book The Ruy Lopez: Winning Chess with 1 P-K4 (1963) by Leonard Barden predates the ECO and calls this variation the "Frankfurt Defence".^[2] They place it towards the "outrageous" end of their list of "irregular and bizarre defences".

While uncertain, the term "Frankfurt Defence" is likely attributed to a 3...Qf6 game between Jean Taubenhaus and Louis Paulsen during the 5th DSB Congress, in Frankfurt, Germany in 1887.^[3]

Documented theory for 3...Qf6 dates back to at least 1843 in the Handbuch des Schachspiels (Handbook of Chess). It cites the dubious line: 4. c3 a6 5. Bxc6 Qxc6 6. O-O Qxe4 7. Nxe5 Be7 8. Re1 Qf5 9. d4 d6 10. Nf3 Be6. The Handbuch notes that white is likely better off with 4. Nc3 instead.^[4]

One of the earliest recorded games of 3...Qf6 was played in Howard Staunton vs Bernhard Horwitz at the then London Chess Club in 1846.^[5]

In 2021, Grandmaster Aman Hambleton experimented with this opening and, finding there was no official name for it in the ECO, gave it the eponym "The Hambleton Defense" and noted its tricky king-side play.^[6]

The Chess.com opening book refers to the opening as the "Ruy López Opening: Gunderam Variation" apparently by analogy with the Gunderam defence, 1. e4 e5 2. Nf3 Qe7. In the Gunderam defence, Black also defends the e5 pawn with the queen, but this involves an early Qe7 not Qf6 and Gerhart Gunderam is not known to have had an affiliation with 3...Qf6.

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

1. e4 e5 2. Nf3 Nc6 3. Bb5 Qf6

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