French Defense - Delayed Exchange Variation - Repertoire Preparation for White
The idea behind delaying the exchange in "French defense - delayed exchange variation" is that we get Black to commit. For instance, if Black plays ...Nc6, then we get Bg5, pinning the knight. Likewise, on ...Nc6, we get the Bb5. Ultimately, against the ...Bb4, which pins our knight, when we exchange, we can claim that Black's knight on b4 is misplaced.
It is thus, that White gets a nagging edge in French Exchange.
We will start with the main line and most common one - 3... Bb4.
The definitive game: Larsen Portisch 1964: This was the first time that Larsen uncorked the Qf3 idea. Portisch reacted incorrectly by castling on the King side. He came under an incredibly serious kingside attack, and succumbed. This game forever put the idea of king side castling against 5.Qf3 to rest.
Note the brilliant 15.a3 move.
Black can react more sensibly by castling on the queen side. We see a more contemporary game between Tim Taylor and Tatev Abrahamyan here.