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

3...Qf6!? is a rare and provocative sideline in the Ruy López. 3...Qf6 aids in the defence of the e5 pawn as well as the knight on c6. Further, the queen adds additional latent pressure to d4, affecting how White may achieve the c3 and d4 pawn push. From its position on the king's side, it has the potential to be involved in a future kingside attack.

This defence ignores conventional wisdom not to develop one's queen early lest it come under attack, but is difficult for White to immediately refute. As the king's knight is denied its usual post on f6, Black typically plays ...Nge7, from where the knight controls d5 and discourages Bxc6. Black may develop their king's bishop to ...Bc5 or ...Bd6, if they can do so before playing ...Nge7, or to ...Bg7. Their queen's bishop is often developed quite late, or fianchettoed.

White's three main plans are to take space in the centre, with 4. c3 followed by d4; to castle, 4. O-O; or 4. Nc3, which threatens a direct confrontation with Black's "offside" queen, 5. Nd5!.

4. c3, readying d4, may be the most natural move because c3 & d4 is the standard plan for White in the Ruy López. Black can respond with ...Nge7, ...Bd6, ...Bc5, or ...a6, but their best and sharpest response is the provocative 4...g5, beginning kingside expansion and threatening ...g4 to kick White's knight.^[1] 5. d4 g4 6. Nxe5 Nxe5 7. dxe5 Qxe5 8. Bd3□±.

Black cannot stop d4. If 4...a6 5. Ba4 Bc5 6. d4! exd4?! (see diagram A), rather than take back cxd4? immediately (Black has three attackers to White's two defenders) White has the intermezzo 7. e5! shooing Black's queen from control of d4. Black's queen must move else be taken because 7...Nxe5? loses to 8. Qe2!, pinning and winning (9. Nxe5) the knight.

4. O-O is the other most natural move in the Spanish. In this case it may be a small inaccuracy, because the time it gives Black to develop makes it harder to achieve c3 and d4. Compare 4. O-O a6 5. Ba4 Bc5 6. c3 Nge7 7. d4 exd4 (diagram B) to the position in diagram A: the intermezzo 8. e5? fails to ...Nxe5, because Qe2 no longer pins the knight.

4. Nc3 is a less obvious move to play in the Spanish, because it interferes with the plan of c3 and d4. However, it makes the most direct attempt to "punish" Black's unprincipled play by threatening 5. Nd5, which both displaces Black's queen from support of the centre and threatens Nxc7+.

If 4...a6 5. Nd5! Qd8, while White has won tempo on the queen, they have not in fact won the pawn:

• Though Black has had to undefend e5, White cannot win the pawn as 6. Bxc6? dxc6! comes with tempo on the knight. After 7. Nc3 (transposing to the Keres variation of the exchange Spanish) Black has time to defend e5 again with 7...f6 or 7...Qd6.
• Similarly, as is often the way, 6. Ba4 Nf6 does not threaten to win White's "undefended" e-pawn either, due to tactics involving Black's uncastled king. (e.g. 7. c3 Nxe4? 8. d4 exd4? 9. Qe2! etc.)

Instead, the role of 4. a6 5. Nd5! is more one of latent pressure that Black cannot remove easily. The engine line is 6. Ba4 Nf6 7. c3 Nxd5 8. exd5 e4! 9. dxc6! exf3 10. cxd7+ Bxd7 11. Bxd7+ Qxd7 12. Qxf3±, where Black gives up a pawn to remove it.

Aman Hambleton prefers to meet 4. Nc3 with 4...Bd6!? (defending c7 and e5) so that 5. Nd5 can be met with 5...Qg6, attacking g2 and e4. Though the engine is happy to castle and give up the e-pawn (6. O-O Qxe4 7. Nc3 Qg6 8. d4±), the resulting positions are razor-sharp and 6. d3 also works as the g2 pawn is poisonous (of course).

Best for Black is 4...Nge7, to deny White Nd5 (or to trade knights if they play it anyway).

3...Qf6 has no official name in the Encyclopaedia of Chess Openings (ECO). The book The Ruy Lopez: Winning Chess with 1 P-K4 (1963) by Leonard Barden, predating the ECO, calls this variation the "Frankfurt Defence".^[2] They place it towards the "outrageous" end of their list of "irregular and bizarre defences". Barden doesn't provide an attribution but the name presumably comes from Jean Taubenhaus v Louis Paulsen during the 5th DSB Congress, held Frankfurt, Germany in 1887.^[3]

Documented theory for 3...Qf6 dates back to at least 1843 in Handbuch des Schachspiels (German: 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 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 Defence" 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.

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

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