user8694: What is this line/trap in the Caro-Kann called?
If Black plays Bf5 on move 3, White chases Black's bishop around with several aggressive pawn moves (similar to the Tal variation) with the ultimate goal of playing e6 (a lethal pawn sacrifice). If White accepts, then Qg6+ Kd7 and a king walk to the queenside can follow. It's also dubious how the kingside bishop and rook will ever develop. Black will likely lose if they don't know the key moves c5 (a counter-sacrifice) and Nf6.
I informally call this the Double Advance variation  since the Advance Variation is characterized by White-e5 and this one is characterized by a subsequent White-e6.
Here an example game where I was Black. This line gets played against me rarely at my level, but regularly by 1800+ players.
[FEN ""]
[Event "Live Chess"]
[Site "Chess.com"]
[Date "2021.09.11"]
[Round "-"]
[White "Naxmanovich (1600)"]
[Black "xjcl (1588)"]
[Result "0-1"]
[CurrentPosition "k2r2r1/pp6/8/5Q2/7P/6qK/PP6/R7 w - -"]
[Timezone "UTC"]
[ECO "B12"]
[ECOUrl "https://www.chess.com/openings/Caro-Kann-Defense-Advance-Bayonet-Attack"]
[UTCDate "2021.09.11"]
[UTCTime "13:42:05"]
[WhiteElo "1600"]
[BlackElo "1588"]
[TimeControl "900+10"]
[Termination "xjcl won by checkmate"]
[StartTime "13:42:05"]
[EndDate "2021.09.11"]
[EndTime "14:20:05"]
[Link "https://www.chess.com/game/live/25106523433"]

1. e4 c6 2. d4 d5 3. e5 Bf5 4. g4 Be4 5. f3 Bg6 6. h4 h6 7. e6 fxe6 8. Bd3 Bxd3
9. Qxd3 Nf6 10. Qg6+ Kd7 11. Bf4 c5 12. Ne2 Nc6 13. c3 Qa5 14. Nd2 cxd4 15. cxd4
Rc8 16. O-O Qb5 17. Rfe1 Qb6 (17... Nb4 18. Nc3 Qd3) 18. Nb3 e5 19. Nc5+ Kc7 20.
Ne6+ Kb8 21. Bg3 Ka8 22. Nxf8 Rcxf8 23. Qxg7 Ne8 24. Qg6 Rxf3 25. Kg2 Rff8
(25... e4) 26. Bxe5 Nf6 (26... Nxe5 27. Qxb6) 27. Bxf6 exf6 28. Qf5 h5 29. Kh3
(29. gxh5) 29... hxg4+ 30. Qxg4 Rhg8 31. Qf5 Nxd4 32. Qxd5 Nc2 33. Qe4 Nxa1 34.
Rxa1 f5 35. Qd3 Rd8 36. Qxf5 Qe3+ 37. Ng3 Qxg3# 0-1


e4 c6 2. d4 d5 3. e5 Bf5 4. g4 Be4 5. f3 Bg6 6. h4 h6 7. e6 fxe6 8. Bd3 Bxd3 9. Qxd3 Nf6 10. Qg6+ Kd7 11. Bf4 c5 12. Ne2 Nc6 13. c3 Qa5 14. Nd2 cxd4 15. cxd4
Rc8 16. O-O Qb5 17. Rfe1 Qb6 (17... Nb4 18. Nc3 Qd3) 18. Nb3 e5 19. Nc5+ Kc7 20.
Ne6+ Kb8 21. Bg3 Ka8 22. Nxf8 Rcxf8 23. Qxg7 Ne8 24. Qg6 Rxf3 25. Kg2 Rff8
(25... e4) 26. Bxe5 Nf6 (26... Nxe5 27. Qxb6) 27. Bxf6 exf6 28. Qf5 h5 29. Kh3
(29. gxh5) 29... hxg4+ 30. Qxg4 Rhg8 31. Qf5 Nxd4 32. Qxd5 Nc2 33. Qe4 Nxa1 34.
Rxa1 f5 35. Qd3 Rd8 36. Qxf5 Qe3+ 37. Ng3 Qxg3# 0-1


user3884: In the advanced Caro, 4. g4 is known as the Bayonet attack. However, the main way to play in response to it is to play Bd7 because this h4-h5 + e6 pawn sacrifice is well-known to be good for white.
As black, you should basically transpose directly into a French defense with your bishop on d7 - following up with e6, c5, Nc6, etc. This is strong because in the French, an early g4 can be actively harmful to white (h5 from black can be played as an interesting pawn sacrifice to gain control of f5 again and forever stop white from playing the thematic f5 pawn break!), and if white doesn't gain any tempi on your bishop, it's not clear why white is playing this way at all. White needs to play quite differently to a normal French in order to justify 4. g4, and overall black should be fine in a line like the following:
[FEN ""]
1. e4 c6 2. d4 d5 3. e5 Bf5 4. g4 Bd7 5. Be3 e6 (5...h5!?) 6. Nf3 c5 7. dxc5 Qc7=


8694: <p>What is this line/trap in the Caro-Kann called?</p>
<p>If Black plays Bf5 on move 3, White chases Black's bishop around with several aggressive pawn moves (similar to the Tal variation) with the ultimate goal of playing e6 (a lethal pawn sacrifice). If White accepts, then Qg6+ Kd7 and a king walk to the queenside can follow. It's also dubious how the kingside bishop and rook will ever develop. Black will likely lose if they don't know the key moves c5 (a counter-sacrifice) and Nf6.</p>
<p>I informally call this the <em><strong>Double Advance</strong></em> variation  since the <em>Advance Variation</em> is characterized by White-e5 and this one is characterized by a subsequent White-e6.</p>
<p>Here an example game where I was Black. This line gets played against me rarely at my level, but regularly by 1800+ players.</p>
<pre><code>[FEN &quot;&quot;]
[Event &quot;Live Chess&quot;]
[Site &quot;Chess.com&quot;]
[Date &quot;2021.09.11&quot;]
[Round &quot;-&quot;]
[White &quot;Naxmanovich (1600)&quot;]
[Black &quot;xjcl (1588)&quot;]
[Result &quot;0-1&quot;]
[CurrentPosition &quot;k2r2r1/pp6/8/5Q2/7P/6qK/PP6/R7 w - -&quot;]
[Timezone &quot;UTC&quot;]
[ECO &quot;B12&quot;]
[ECOUrl &quot;https://www.chess.com/openings/Caro-Kann-Defense-Advance-Bayonet-Attack&quot;]
[UTCDate &quot;2021.09.11&quot;]
[UTCTime &quot;13:42:05&quot;]
[WhiteElo &quot;1600&quot;]
[BlackElo &quot;1588&quot;]
[TimeControl &quot;900+10&quot;]
[Termination &quot;xjcl won by checkmate&quot;]
[StartTime &quot;13:42:05&quot;]
[EndDate &quot;2021.09.11&quot;]
[EndTime &quot;14:20:05&quot;]
[Link &quot;https://www.chess.com/game/live/25106523433&quot;]

1. e4 c6 2. d4 d5 3. e5 Bf5 4. g4 Be4 5. f3 Bg6 6. h4 h6 7. e6 fxe6 8. Bd3 Bxd3
9. Qxd3 Nf6 10. Qg6+ Kd7 11. Bf4 c5 12. Ne2 Nc6 13. c3 Qa5 14. Nd2 cxd4 15. cxd4
Rc8 16. O-O Qb5 17. Rfe1 Qb6 (17... Nb4 18. Nc3 Qd3) 18. Nb3 e5 19. Nc5+ Kc7 20.
Ne6+ Kb8 21. Bg3 Ka8 22. Nxf8 Rcxf8 23. Qxg7 Ne8 24. Qg6 Rxf3 25. Kg2 Rff8
(25... e4) 26. Bxe5 Nf6 (26... Nxe5 27. Qxb6) 27. Bxf6 exf6 28. Qf5 h5 29. Kh3
(29. gxh5) 29... hxg4+ 30. Qxg4 Rhg8 31. Qf5 Nxd4 32. Qxd5 Nc2 33. Qe4 Nxa1 34.
Rxa1 f5 35. Qd3 Rd8 36. Qxf5 Qe3+ 37. Ng3 Qxg3# 0-1
</code></pre>
<ol>
<li>e4 c6 2. d4 d5 3. e5 Bf5 4. g4 Be4 5. f3 Bg6 6. h4 h6 7. e6 fxe6 8. Bd3 Bxd3 9. Qxd3 Nf6 10. Qg6+ Kd7 11. Bf4 c5 12. Ne2 Nc6 13. c3 Qa5 14. Nd2 cxd4 15. cxd4
Rc8 16. O-O Qb5 17. Rfe1 Qb6 (17... Nb4 18. Nc3 Qd3) 18. Nb3 e5 19. Nc5+ Kc7 20.
Ne6+ Kb8 21. Bg3 Ka8 22. Nxf8 Rcxf8 23. Qxg7 Ne8 24. Qg6 Rxf3 25. Kg2 Rff8
(25... e4) 26. Bxe5 Nf6 (26... Nxe5 27. Qxb6) 27. Bxf6 exf6 28. Qf5 h5 29. Kh3
(29. gxh5) 29... hxg4+ 30. Qxg4 Rhg8 31. Qf5 Nxd4 32. Qxd5 Nc2 33. Qe4 Nxa1 34.
Rxa1 f5 35. Qd3 Rd8 36. Qxf5 Qe3+ 37. Ng3 Qxg3# 0-1</li>
</ol>
 3884: <p>In the advanced Caro, 4. g4 is known as the Bayonet attack. However, the main way to play in response to it is to play Bd7 because this h4-h5 + e6 pawn sacrifice is well-known to be good for white.</p>
<p>As black, you should basically transpose directly into a French defense with your bishop on d7 - following up with e6, c5, Nc6, etc. This is strong because in the French, an early g4 can be actively harmful to white (h5 from black can be played as an interesting pawn sacrifice to gain control of f5 again and forever stop white from playing the thematic f5 pawn break!), and if white doesn't gain any tempi on your bishop, it's not clear why white is playing this way at all. White needs to play quite differently to a normal French in order to justify 4. g4, and overall black should be fine in a line like the following:</p>
<pre><code>[FEN &quot;&quot;]
1. e4 c6 2. d4 d5 3. e5 Bf5 4. g4 Bd7 5. Be3 e6 (5...h5!?) 6. Nf3 c5 7. dxc5 Qc7=
</code></pre>
