He saw h5. This meant Qg6 and a pawn drops.

But, he had to see even deeper than this, because with two rooks, when they really go to work, they can win any pawn, and the queen can't defend.

[unknown player]

supposing R[a]d8 to hold the knight.
20. Rh8+ Kf7 R[1] h7+ Kg6

now it is mate in 5 - have fun!

Heh. By coincidence, I played a tournament game last weekend where - as Black in the French - I reached an eminently winnable position with Queen (and outside passed pawn) versus two Rooks.

Initiative is the key. It's actually the only viable strategy, because the Queen is such a poor defender. You aim to target your opponent's weaker pawns, while steadily improving your King position, and using tactical threats - mates, pins, skewers, forks - to restrict the mobility of the enemy King and Rooks.

Of course the Rooks have the firepower to concentrate forces on an isolated pawn and win it. The trick is to make sure that any such attack leads to mass exchanges and a winning pawn ending, usually because the enemy King has been lured or driven away from its own pawns.

You have to be careful, in most cases, not to advance your passer too quickly -- except, of course, in positions where the defending pieces are temporarily placed on awkward squares, and you can ram the pawn home before they regroup.

It sounds more complicated than it is. Having said that, my game went wrong ... I missed a couple of clear wins, then dropped my passed pawn in a position where my opponent could hold the draw by a single tempo.

Which is how a moment of carelessness after 80 moves turns a win into a draw. I didn't even learn from the experience, because I did almost exactly the same thing in the next round, this time in a Rook ending with an extra pawn. A win until move 85, when I inexplicably let it slip to a draw.

Sigh.

Oh, and the answer to the question about the French? There are many other sub-variations out there. I've played the French for 30 years without once feeling the need to play this 3...Nf6 4.Bg5 dxe4 line.

Great a calculator as Fischer was, this comes under the oft-amorphous heading of judgment, as there's little doubt in my mind that he had intended this when playing the committal 16.gxf3 instead of the natural 16.Rxf3.

Once White plays 16.gxf3, he is forced to attack, as he may count himself lucky to hold any of these endings with heavy pieces, particularly if queens should come off.

Even a much weaker player like myself can see that Black's rooks have trouble getting co-ordinated, but only a player with the technical mastery of Fischer can make the winning process look simple.

Three or 4 posters have given excellent responses to this question. I will now give a cynical response:

In the French Defense, the first player to castle will nearly always lose.

click for larger view

"This position could have occurred in my game with the Hungarian Grandmaster Bilek in the 1965 Havana Tournament. My opponent avoided this position."