Here is a tense position from the game Fine-Reshevsky, A.V.R.O. 1938 (first diagram). White – to play – is a pawn down, and he obviously wants to win it back before Black can consolidate. The pawn on a6 is the natural target.
Theatening 17.Bxa6, which is not easy to meet directly because of the pressure against Black's e-pawn.
A counterattack against the central light squares, and against White's queen in particular.
In the actual game, Fine prevented the threat of ...Nf4 by playing 17.g3. The matter of interest today is Reshevsky's analysis of 17.Bxa6. In his book Reshevsky on Chess (1948) he gave the following line:
17...Nf4 18.Qf1 Rxa6 19.Qxa6 Rb8 (second diagram)
and wrote that “White is helpless against the threat of ...Bb5.”
It is obvious that White cannot prevent ...Bb5, so things are certainly looking grim. What is not obvious is that White has a defence – more precisely, a counterattack. How about this:
Making a square for the queen on a5, and also attacking the knight.
Pushing ahead with the plan of trapping White's queen. The alternatives are less promising:
A. 20...Nb3? 21.Nxb3 axb3 22.Bxf4 exf4 23.Qa3 and White is simply the exchange up with a clear advantage;
B. 20...Rxb4 21.Ba3 (or the more complex 21.dxe5 Bc8 22.exd6 Bxd6 23.Qf1 Rb6 24.e5 Bc5 25.Re4, etc.) 21...Bc8 22.Qf1 Rb6 23.Rec1! (winning time to make space for the queen) 23...Qd7 24.Nc4 Nxc4 25.Qxc4 Ba6 26.Qc7 Ne2+ 27.Kh2 and White is again up the exchange, although Black's bishop pair is also a factor;
C. 20...Nc6 21.Qxa4 Nxd4 21.Qa5 with equality.
Now Black is threatening 22...Bd8, so White needs to find another resource.
White does have an extra rook, so that gives him the option of returning it in order to extricate his queen.
White's queen escapes after 22...Bd8 23.Qa7 (also interesting is 23.Qa8!?, aiming to get two rooks for the queen) 23...Rb7 24.Qa8 (here too 24.Qxb7!? is possible) 24...Bxa4 25.dxe5. Here White must still tread carefully but having all the pawns on one side of the board is the key leveling factor.
23.dxe5! Nd3 24.Rf1
White has survived the complications and reached an equal position.
Does this mean that White can recover the pawn with 17.Bxa6? Of course not. After 17...Nf4 18.Qf1 Black has a much stronger way to exploit the light squares:
Now if 19.Bxc8? then 19...Bb5 wins easily for Black. White must retreat his bishop:
White is again a pawn down but can play to win it back by gaining a tempo on Black's knight.
20.Nc4 Nxc4 21.Bxc4 Be6!
The most accurate way to preserve the advantage. Now if 22.Bxe6 then 22...Nxe6 and Black keeps the extra pawn. Of course White cannot contemplate 22.Bxf4? Bxc4 and wins.
22.Bb5 Ng6 23.Rd1
With this move White clears a square for his queen and renews the threat to recover the pawn.
Consolidating the more important pawn.
24.Rxa4 Rxa4 25.Bxa4 Bc4 26.Qe1 Qa6!
Taking control of the key diagonal without loss of time.
27.b3 Be2! 28.Rd2 Bxf3 29.gxf3 Nh4! (third diagram)
The culmination of Black's strategy commencing with 18...Qb6! The strategic advantage of controlling the a6-f1 diagonal has been transformed into a decisive advantage in pawn structure.
One might say that Reshevsky had the right idea, but did not show the right way to execute it.