Answers.Body: <p>Six units (verified by both the Nalimov and Syzygy tablebases):</p>
  <pre><code>[Title &quot;NDE(?) after Lazard: White to move and draw&quot;]
  [FEN &quot;8/1P7/r4k1b/8/8/8/p7/K7 w - - 0 1&quot;]
  
  1. b8=R! Bg7 2. Rb2!
  </code></pre>
  <p>It's easier to modify the Lazard position to a 7-unit setting:</p>
  <pre><code>[Title &quot;Lazard 1935, v. NDE: WTM and draw&quot;]
  [FEN &quot;8/4bP2/8/8/8/3p2k1/3Pp/4K3 w - - 0 1&quot;]
  
  1. f8=R! Bh4! 2. Rf2!
  </code></pre>
  <p>As in Lazard's study, the final position is mutual Zugzwang:
  if it were White to move, Black would win (e.g. 3 Rxe2 Kf3+).
  This also works with the Black Bishop on g5, f6, or d8 instead of e7.</p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2024-06-06T21:36:56.093Z
Answers.Text: Congratulations - wonderful stuff
Answers.UserDisplayName: Laska
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2024-06-06T20:05:17.307Z
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Answers.UserDisplayName: Noam D. Elkies
Answers.Body: <p>I think I found a position with <strong>7 units</strong></p>
  <pre><code>[Title &quot;White to play and draw&quot;]
  [FEN &quot;6Kn/6PP/6kb/7r/8/8/8/8 w - - 0 1&quot;]
  
  1. gxh8=R! Rf5
  </code></pre>
  <p>1.gh8Q? (or 1.gh8B?) loses to 1...Rf5!</p>
  <p>1.Kh8? (or 1.Kf8?) loses to 1...Bxg7</p>
  <p>1.gh8N!? Kf6 2.Ng6/Nf7 Bg7 3.h8Q Bxh8 4.Nxh8 Ra5 is a theoretical win : 5.Kh7 Ra3 6.Kg8 Ra4 7.Kh7 Rg4Z -+</p>
  <p>But the rook promotion <strong>1.gh8R!=</strong> saves the day with the stalemate trick. Black can call it a day with 1...Rf5= or let White escape with 1...Kf5 or 1...Be3 to a drawn R+B vs R endgame, but they cannot win.</p>
  <hr />
  <p>Previous answer :</p>
  <p>A bid with 8 men. I am sure that 7 is possible, I don't know about 6.</p>
  <pre><code>[Title &quot;White to play and draw&quot;]
  [FEN &quot;K7/PP6/P7/8/7k/6b1/1p6/1b6 w - - 0 1&quot;]
  
  1. b8=R! Be4 2. Rb7 b1=Q
  </code></pre>
  <p>1.b8Q? Be4+ 2.Qb7 b1Q (or 2...b1B) mates on the next move.</p>
  <p>1.b8R! Be4+ (1...Be5 2.Rb4+=) 2.Rb7 Bxb7 (most other moves are stalemate) 3.ab b1Q 4.b8Q=</p>
  
Answers.ContentLicense: CC BY-SA 4.0
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Answers.UserDisplayName: Evargalo
Answers.Body: <p>This 7-unit draw-study is in <a href="https://pdb.dieschwalbe.de/" rel="nofollow noreferrer">PDB</a> with id P1394451.</p>
  <pre><code>[Title &quot;Marek Kacewicz; Szachy, Jun 1980, 36v&quot;]
  [StartFlipped &quot;0&quot;]
  [fen &quot;8/p2b4/PP5b/K7/5k2/8/8/8 w - - 0 1&quot;]
  
  1.b7! Ke4 2. b8=R! Bd2+ 3. Rb4+ Bxb4+ 4. Kxb4 Kd3 5. Kb3 Be6+ 6. Kb2=
  </code></pre>
  <p>(If 2 b8=Q? then 2 ... Bd2+ 3. Qb4+ Kd3! 4. Qxd2+ Kxd2 and Black wins.)</p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2024-06-05T19:38:21.797Z
Answers.Text: Very nice study ! I was not too far from this matrix with my 8-men position...
Answers.UserDisplayName: Evargalo
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Answers.CreationDate: 2024-06-05T16:27:46.317Z
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Answers.UserDisplayName: Rosie F
Body: <p>How many pieces and pawns are needed for a position where:</p>
  <ul>
  <li>White has only one move to draw</li>
  <li>That move is a rook promotion</li>
  <li>All other moves by white lose</li>
  </ul>
  <p>I know this position with 9 pieces and pawns:</p>
  <pre><code>[Title &quot;F. Lazard, 1935&quot;]
  [FEN &quot;8/3P4/3b4/8/8/1p2k2p/1Pp4P/2K5 w - - 0 1&quot;]
  
  1. d8=R! Bf4 2. Rd2!
  </code></pre>
  
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2024-06-04T08:37:24.623Z
Comments.Text: https://lichess.org/forum/general-chess-discussion/drawing-by-underpromotion?page=2, last posting, play to R promotion at the end, have 8. (Jan Rusinek, 64, 1978)
Comments.UserDisplayName: Hauke Reddmann
Tags: <pawn-promotion>
Title: Simplest position where promotion to rook is unique drawing move
ThreadText: # Simplest position where promotion to rook is unique drawing move
  
  (Asked by: username_0 on 2024-06-03)
  
  How many pieces and pawns are needed for a position where:
  
  * White has only one move to draw
  * That move is a rook promotion
  * All other moves by white lose
  
  I know this position with 9 pieces and pawns:
  
  ```
  [Title "F. Lazard, 1935"]
  [FEN "8/3P4/3b4/8/8/1p2k2p/1Pp4P/2K5 w - - 0 1"]
  
  1. d8=R! Bf4 2. Rd2!
  
  ```
  
  **Tags:** pawn-promotion
  
  > **Comments:**
  > **username_1**: https://lichess.org/forum/general-chess-discussion/drawing-by-underpromotion?page=2, last posting, play to R promotion at the end, have 8. (Jan Rusinek, 64, 1978)  
  
  ---
  
  ## 3 answers
  
  ### Answer by username_2 on 2024-06-06. Score: 4 | Accepted answer
  
  Six units (verified by both the Nalimov and Syzygy tablebases):
  
  ```
  [Title "NDE(?) after Lazard: White to move and draw"]
  [FEN "8/1P7/r4k1b/8/8/8/p7/K7 w - - 0 1"]
  
  1. b8=R! Bg7 2. Rb2!
  
  ```
  
  It's easier to modify the Lazard position to a 7-unit setting:
  
  ```
  [Title "Lazard 1935, v. NDE: WTM and draw"]
  [FEN "8/4bP2/8/8/8/3p2k1/3Pp/4K3 w - - 0 1"]
  
  1. f8=R! Bh4! 2. Rf2!
  
  ```
  
  As in Lazard's study, the final position is mutual Zugzwang:
  if it were White to move, Black would win (e.g. 3 Rxe2 Kf3+).
  This also works with the Black Bishop on g5, f6, or d8 instead of e7.
  
  > **Comments:**
  > **username_3**: Congratulations - wonderful stuff  
  
  ---
  
  ### Answer by username_4 on 2024-06-04. Score: 5
  
  I think I found a position with **7 units**
  
  ```
  [Title "White to play and draw"]
  [FEN "6Kn/6PP/6kb/7r/8/8/8/8 w - - 0 1"]
  
  1. gxh8=R! Rf5
  
  ```
  
  1.gh8Q? (or 1.gh8B?) loses to 1...Rf5!
  
  1.Kh8? (or 1.Kf8?) loses to 1...Bxg7
  
  1.gh8N!? Kf6 2.Ng6/Nf7 Bg7 3.h8Q Bxh8 4.Nxh8 Ra5 is a theoretical win : 5.Kh7 Ra3 6.Kg8 Ra4 7.Kh7 Rg4Z -+
  
  But the rook promotion **1.gh8R!=** saves the day with the stalemate trick. Black can call it a day with 1...Rf5= or let White escape with 1...Kf5 or 1...Be3 to a drawn R+B vs R endgame, but they cannot win.
  
  ---
  
  Previous answer :
  
  A bid with 8 men. I am sure that 7 is possible, I don't know about 6.
  
  ```
  [Title "White to play and draw"]
  [FEN "K7/PP6/P7/8/7k/6b1/1p6/1b6 w - - 0 1"]
  
  1. b8=R! Be4 2. Rb7 b1=Q
  
  ```
  
  1.b8Q? Be4+ 2.Qb7 b1Q (or 2...b1B) mates on the next move.
  
  1.b8R! Be4+ (1...Be5 2.Rb4+=) 2.Rb7 Bxb7 (most other moves are stalemate) 3.ab b1Q 4.b8Q=
  
  
  ---
  
  ### Answer by username_5 on 2024-06-05. Score: 3
  
  This 7-unit draw-study is in [PDB](https://pdb.dieschwalbe.de/) with id P1394451.
  
  ```
  [Title "Marek Kacewicz; Szachy, Jun 1980, 36v"]
  [StartFlipped "0"]
  [fen "8/p2b4/PP5b/K7/5k2/8/8/8 w - - 0 1"]
  
  1.b7! Ke4 2. b8=R! Bd2+ 3. Rb4+ Bxb4+ 4. Kxb4 Kd3 5. Kb3 Be6+ 6. Kb2=
  
  ```
  
  (If 2 b8=Q? then 2 ... Bd2+ 3. Qb4+ Kd3! 4. Qxd2+ Kxd2 and Black wins.)
  
  > **Comments:**
  > **username_4**: Very nice study ! I was not too far from this matrix with my 8-men position...  
  
  ---
  
  