Some of the posts are on-target, some are off-target. Here are my notes:
- I just don't think any Caro-Kann player who knows the defense will have a problem with any f3-style Blackmar-Diemer gambit.
- I've played the Caro-Kann for many years. I don't play 1.e4, but in a Caro-Kann tournament I played in on chess.com recently, I played the Panov-Botvinnik attack exclusively as white. (1.e4 c6 2.d4 d5 3.exd5 cxd5 4.c4). As pointed out above, it is basically a d4-style game where white gets an isolated queen's pawn. As you can imagine, some of the main positions can be reached from more than one opening (Queen's Gambit Tarrasch or Nimzo-Indian are two examples).
- If I had only 30 minutes to prepare someone to play the white side, I would recommend the simple exchange variation, without c4. It's not a variation which is theoretically critical, but winning a theoretical battle against a well-prepared opponent is not the goal. The goal is getting a playable middlegame where you are at least equal. For reference, the moves might be 1.e4 c6 2.d4 d5 3.exd5 cxd5 4.Bd3 Nc6 5.c3 Nf6 6.Nf3 Bg4 7.Nbd2 e6 8.o-o Bd6 etc. White is playing a queen's gambit exchange variation a tempo up. Can't be bad.
- Recently I've been having trouble against the Advance Variation, specifically the Short Variation where white plays Nf3, Be2, o-o, and tries to exploit the absence of black's queen's bishop on the queenside.
- I'm assuming that the bayonet attack is 1.e4 c6 2.d4 d5 3.e5 Bf5 4.g4?!. I don't think much of this move. An expert-level player played it against me recently in a tournament, and didn't get anything out of the opening. Apparently he said that black usually plays 4. ...Bg6?, which kind of justifies white's play (white can play 5.e6, sacrificing the e pawn with compensation). But I played 4. ...Bd7!, followed by ...Qc8, and (I think) ...h5. My opponent said that "basically everybody plays 4. ...Bg6, except once when I played this against GM Sergey Kudrin, who played ...Bd7. So when you played ...Bd7 I knew that you knew what you were doing". Pretty cool, to be compared with Mr. Kudrin.
-- Ozzie
as a caro devotee, i would give this advice to the 1.e4 player. DONT play into the main line. sure, its just a bunch of piece shifting but when you played 1.e4 you said you wanted to be tactical.black wants you play this.
i (from blacks pov) also like to play the advance variation. i feel it just cuts whites tension.
also the exchange variation (posted above) imo cuts the tension the wrong way too. where spoiler left off black then plays ..Nc6, and white plays 5.c3. so theirs a bit of developmental catchup quick and it just doesnt challenge black enough.
im recommending the PBA, as that echange quickly follows by throwing a pawn at the center, followed by logical-but-pressuring defense.
ask all the caro players which line they least like to play, and theyd say the PBA.. in fact, some will lie.. such as myself awhile back . i said the main line was the hardest lol.. trying to throw people off but now i dont do caro as much so im willing to share.
and finally i might add the fantasy variation is lame, and theres a sideline that slaps it silly.
What is the sideline?