Answers.Body: <p>I think this has to do with central pawn play, in particular white's e-pawn and black's c-pawn.</p>
  <p>White's pawn on e5 is <em>very</em> valuable, and must be protected, and c5 is black's only good pawn break to open the position.</p>
  <p>When c5 eventually gets played, the e-pawn is suddenly under a lot of pressure. Taking on c5 would break the pawn chain with tripled pawns, black already has a knight on d7, and queen to c7 would add yet another attacker.</p>
  <p>White thus has two main goals:</p>
  <ul>
  <li>Add defenders to the e-pawn</li>
  <li>Keep some control over the c5 square.</li>
  </ul>
  <p>Here we see the main moves crystallize out: Moving the rook to e1 adds a defender, and Bf4 or the Bf2-Bg3 manoeuvre recruits the bishop as well (both unblocking the future e-file rook). The difference between the two bishop moves is that Bf2 keeps the bishop on the same diagonal as the key c5 square.</p>
  <p>A concrete variation to illustrate this difference:</p>
  <p>Black can attack the queen, threaten a fork, and thus achieve c5, for some activity and a still somewhat playable position</p>
  <pre><code>[title &quot;Bf4&quot;]
  [fen &quot;r2q1rk1/pp1n1pp1/1np1p2p/4P3/2PP4/2PQBN2/P5PP/1R3RK1 w - - 0 4&quot;]
  
  1.Bf4 Nc5 2.Qe2 Nca4 3.Qc2 c5
  </code></pre>
  <p>The same line would go horribly wrong if the bishop moved to f2 instead, ending up in black losing a knight.</p>
  <pre><code>[title &quot;Bf2&quot;]
  [fen &quot;r2q1rk1/pp1n1pp1/1np1p2p/4P3/2PP4/2PQBN2/P5PP/1R3RK1 w - - 0 4&quot;]
  
  1.Bf2 Nc5 2.Qe2 Nca4 3.Qc2 c5 4.dxc5
  </code></pre>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2023-05-09T09:03:05.410Z
Answers.LastActivityDate: 2023-05-09T09:21:00.380Z
Answers.LastEditDate: 2023-05-09T09:21:00.380Z
Answers.UserDisplayName: SE - stop firing the good guys
Body: <p>In the <a href="https://lichess.org/ca5y7U1t/white#28" rel="nofollow noreferrer">following position</a> from a Caro-Kann fantasy gone wrong, the engine suggests 15.Bf2 with advantage of (+2.5) among other close-by candidates such as Bf4 (+2.2) and Rfe1 (+2.0).</p>
  <pre><code>[Title &quot;White to move&quot;]
  [FEN &quot;r2q1rk1/pp1n1pp1/1np1p2p/4P3/2PP4/2PQBN2/P5PP/1R3RK1 w - - 2 15&quot;]
  
  1. Bf2
  </code></pre>
  <p>But why? On the surface level, I see some immediate disadvantages:</p>
  <ul>
  <li>Primary: Blocks in the f-rook.</li>
  <li>Medium: Disallows Bd2 to defend against Na4. (Though Qc2 can also do that.)</li>
  <li>Lesser: Reduces control over Qg5 and removes possibility of (unlikely) Bxh6.</li>
  </ul>
  <p>I do see some smaller advantages:</p>
  <ul>
  <li>Bg3 supports an eventual Nd6.</li>
  <li>Out-of-pawn-chain mobility: Bh4 is possible to control f6 and d8.</li>
  <li>Bishop is &quot;less vulnerable&quot;... though it is unclear what could attack it anyways. f5-f4 looks silly since exf6 creates an isolated e6 pawn.</li>
  <li>If Rfe1 is next, it's advantageous to have already vacated the e-file.</li>
  </ul>
  
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2023-05-09T08:51:55.647Z
Comments.Text: Bh4, Nd2 Ne4 could be one. alo Bh4 g5 Nxg5 hxg5 Qg3 looks interesting but didn't calculate. try moving the rook back and forth a8-c8. engine will reveal what Bf2 was up to?
Comments.UserDisplayName: cmgchess
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2023-05-09T10:58:15.673Z
Comments.Text: *Out-of-pawn-chain mobility: Bh4 is possible to control f6 and d8.* -> yup, this is it !
Comments.UserDisplayName: Evargalo
Tags: <positional-play><caro-kann>
Title: The case of the mysterious retreating bishop
ThreadText: # The case of the mysterious retreating bishop
  
  (Asked by: username_0 on 2023-05-09)
  
  In the [following position](https://lichess.org/ca5y7U1t/white#28) from a Caro-Kann fantasy gone wrong, the engine suggests 15.Bf2 with advantage of (+2.5) among other close-by candidates such as Bf4 (+2.2) and Rfe1 (+2.0).
  
  ```
  [Title "White to move"]
  [FEN "r2q1rk1/pp1n1pp1/1np1p2p/4P3/2PP4/2PQBN2/P5PP/1R3RK1 w - - 2 15"]
  
  1. Bf2
  
  ```
  
  But why? On the surface level, I see some immediate disadvantages:
  
  * Primary: Blocks in the f-rook.
  * Medium: Disallows Bd2 to defend against Na4. (Though Qc2 can also do that.)
  * Lesser: Reduces control over Qg5 and removes possibility of (unlikely) Bxh6.
  
  I do see some smaller advantages:
  
  * Bg3 supports an eventual Nd6.
  * Out-of-pawn-chain mobility: Bh4 is possible to control f6 and d8.
  * Bishop is "less vulnerable"... though it is unclear what could attack it anyways. f5-f4 looks silly since exf6 creates an isolated e6 pawn.
  * If Rfe1 is next, it's advantageous to have already vacated the e-file.
  
  **Tags:** positional-play, caro-kann
  
  > **Comments:**
  > **username_1**: Bh4, Nd2 Ne4 could be one. alo Bh4 g5 Nxg5 hxg5 Qg3 looks interesting but didn't calculate. try moving the rook back and forth a8-c8. engine will reveal what Bf2 was up to?  
  > **username_2**: *Out-of-pawn-chain mobility: Bh4 is possible to control f6 and d8.* -> yup, this is it !  
  
  ---
  
  ## 1 answers
  
  ### Answer by username_3 on 2023-05-09. Score: 6 | Accepted answer
  
  I think this has to do with central pawn play, in particular white's e-pawn and black's c-pawn.
  
  White's pawn on e5 is *very* valuable, and must be protected, and c5 is black's only good pawn break to open the position.
  
  When c5 eventually gets played, the e-pawn is suddenly under a lot of pressure. Taking on c5 would break the pawn chain with tripled pawns, black already has a knight on d7, and queen to c7 would add yet another attacker.
  
  White thus has two main goals:
  
  * Add defenders to the e-pawn
  * Keep some control over the c5 square.
  
  Here we see the main moves crystallize out: Moving the rook to e1 adds a defender, and Bf4 or the Bf2-Bg3 manoeuvre recruits the bishop as well (both unblocking the future e-file rook). The difference between the two bishop moves is that Bf2 keeps the bishop on the same diagonal as the key c5 square.
  
  A concrete variation to illustrate this difference:
  
  Black can attack the queen, threaten a fork, and thus achieve c5, for some activity and a still somewhat playable position
  
  ```
  [title "Bf4"]
  [fen "r2q1rk1/pp1n1pp1/1np1p2p/4P3/2PP4/2PQBN2/P5PP/1R3RK1 w - - 0 4"]
  
  1.Bf4 Nc5 2.Qe2 Nca4 3.Qc2 c5
  
  ```
  
  The same line would go horribly wrong if the bishop moved to f2 instead, ending up in black losing a knight.
  
  ```
  [title "Bf2"]
  [fen "r2q1rk1/pp1n1pp1/1np1p2p/4P3/2PP4/2PQBN2/P5PP/1R3RK1 w - - 0 4"]
  
  1.Bf2 Nc5 2.Qe2 Nca4 3.Qc2 c5 4.dxc5
  
  ```
  
  
  ---
  
  