Answers.Body: <p><code>Kb1</code> is generally played to</p>
  
  <ol>
  <li>Defend the unprotected a2 pawn (from <code>...Qa5</code> for example)</li>
  <li>remove the King from the dangerous c file</li>
  </ol>
  
  <p>If none of the above threats occur, <code>Kb1</code> is not necessary.</p>
  
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2012-05-16T13:44:03.863Z
Answers.LastActivityDate: 2012-06-12T01:27:54.293Z
Answers.LastEditDate: 2012-06-12T01:27:54.293Z
Answers.UserDisplayName: xaisoft
Answers.Body: <p>There are two main reasons to play <code>Kb1(b8)</code>:</p>
  
  <ol>
  <li><p><strong>Prophylaxis</strong> - Kb1 does many things, <a href="https://chess.stackexchange.com/a/472/12">xaisoft's answer</a> touches on some of them.  On c1, the king is very exposed to checks on the c1-h6 diagonal.  This means that a queen could check on g5 and pick off a loose piece on h4.  Or similarly, if black plays <code>...Bh6</code>, the white king will be checked, or worse, a piece could be pinned to the king.  In most openings where white plays O-O-O, the center and kingside pawns are being thrown forward to try and mate black, so avoiding diagonal checks is almost always useful.  Some other reasons that Kb1 is useful are:</p>
  
  <ul>
  <li>Clearing c1 for a rook to help defend c2</li>
  <li>Protecting the a2 pawn</li>
  <li>Preparing to play <code>c3</code> or <code>b3</code> to blunt an attack along the c or b file (although <code>c3</code> is almost always wrong once <code>O-O-O</code> has been played)</li>
  </ul></li>
  <li><p><strong>A Waiting Move</strong> - Since we have already established that <code>Kb1</code> is useful, it is also important to note that there are very few drawbacks to the move.  Other moves might not be so good in the position though.  For example, in the Yugoslav Attack of the Dragon, in current theory white will play <code>12. Kb1</code> instead of <code>12. h4</code> because white is <em>not yet sure</em> how best to deploy the kingside pawns.  Frequently white will just play <code>g4</code> and omit <code>h4</code> to speed up the attack.  </p></li>
  </ol>
  
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2012-05-16T15:26:26.983Z
Answers.Text: +1 for mentioning Kb1 as an (sometimes) useful waiting move.
Answers.UserDisplayName: Ray
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2012-05-16T14:48:12.947Z
Answers.LastActivityDate: 2012-06-12T01:27:39.317Z
Answers.LastEditDate: 2017-04-13T12:48:53.193Z
Answers.UserDisplayName: Andrew
Body: <p>I'm curious about this move duo.</p>
  
  <p>I see this quite a bit, and I'm trying to figure out under which conditions that playing <code>Kb1(b8)</code> is normally preferred.</p>
  
  <p>In some openings, such as the Sicilian Dragon, White will castle long followed up by playing <code>Kb1</code>.  In such cases, there are some rather real threats against the castled position there (<code>Bg7</code> pointing at b2, open c-file with <code>Rc8</code>, active Black Queen).</p>
  
  <p>However, I'm more curious about some of the more quieter positions where there doesn't appear to be any obvious threats.  In some cases, I see players, and even computer programs, play <code>Kb1(b8)</code> immediately.  I've analyzed some of these lines and never seem to find any reason why <code>Kb1(b8)</code> is played.</p>
  
  <p>I've always been of the mind to just leave the King at c1(c8) unless there is some obvious threat.</p>
  
  <p>Why is <code>Kb1(b8)</code> played in some of these positions?  What types of threats can the other player come up with to require <code>Kb1(b8)</code> to be played? </p>
  
Tags: <castling><king-safety>
Title: Playing Kb1(b8) immediately after O-O-O
ThreadText: # Playing Kb1(b8) immediately after O-O-O
  
  (Asked by: username_0 on 2012-05-16)
  
  I'm curious about this move duo.
  
  I see this quite a bit, and I'm trying to figure out under which conditions that playing `Kb1(b8)` is normally preferred.
  
  In some openings, such as the Sicilian Dragon, White will castle long followed up by playing `Kb1`. In such cases, there are some rather real threats against the castled position there (`Bg7` pointing at b2, open c-file with `Rc8`, active Black Queen).
  
  However, I'm more curious about some of the more quieter positions where there doesn't appear to be any obvious threats. In some cases, I see players, and even computer programs, play `Kb1(b8)` immediately. I've analyzed some of these lines and never seem to find any reason why `Kb1(b8)` is played.
  
  I've always been of the mind to just leave the King at c1(c8) unless there is some obvious threat.
  
  Why is `Kb1(b8)` played in some of these positions? What types of threats can the other player come up with to require `Kb1(b8)` to be played?
  
  **Tags:** castling, king-safety
  
  
  ---
  
  ## 2 answers
  
  ### Answer by username_2 on 2012-05-16. Score: 7 | Accepted answer
  
  There are two main reasons to play `Kb1(b8)`:
  
  1. **Prophylaxis** - Kb1 does many things, [username_1's answer](https://chess.stackexchange.com/a/472/12) touches on some of them. On c1, the king is very exposed to checks on the c1-h6 diagonal. This means that a queen could check on g5 and pick off a loose piece on h4. Or similarly, if black plays `...Bh6`, the white king will be checked, or worse, a piece could be pinned to the king. In most openings where white plays O-O-O, the center and kingside pawns are being thrown forward to try and mate black, so avoiding diagonal checks is almost always useful. Some other reasons that Kb1 is useful are:
  
     * Clearing c1 for a rook to help defend c2
     * Protecting the a2 pawn
     * Preparing to play `c3` or `b3` to blunt an attack along the c or b file (although `c3` is almost always wrong once `O-O-O` has been played)
  2. **A Waiting Move** - Since we have already established that `Kb1` is useful, it is also important to note that there are very few drawbacks to the move. Other moves might not be so good in the position though. For example, in the Yugoslav Attack of the Dragon, in current theory white will play `12. Kb1` instead of `12. h4` because white is *not yet sure* how best to deploy the kingside pawns. Frequently white will just play `g4` and omit `h4` to speed up the attack.
  
  > **Comments:**
  > **username_3**: +1 for mentioning Kb1 as an (sometimes) useful waiting move.  
  
  ---
  
  ### Answer by username_1 on 2012-05-16. Score: 5
  
  `Kb1` is generally played to
  
  1. Defend the unprotected a2 pawn (from `...Qa5` for example)
  2. remove the King from the dangerous c file
  
  If none of the above threats occur, `Kb1` is not necessary.
  
  
  ---
  
  