EndgamesPlay as white

Key Squares

Learn how to identify and use key squares — the critical squares that, once occupied by the king, guarantee pawn promotion regardless of the defender's play.

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Introduction

Every passed pawn has key squares — specific squares that, if the attacking king occupies them, guarantee promotion no matter what the defender does. For a pawn that hasn't reached the 5th rank, the key squares are the three squares two ranks ahead of the pawn. In this position, the e3 pawn's key squares are d5, e5, and f5. White's king already stands on e5 — a key square! This means promotion is guaranteed with correct play. The lesson demonstrates *why* occupying a key square wins, and how the key squares shift forward as the pawn advances.

Lesson Content

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View on Analysis Board
1. e4

Advancing the pawn is the fastest winning move. The king already occupies e5, a key square for the e3 pawn, so the position is winning. By pushing to e4, the pawn advances while the king maintains its dominant position. Critically, the key squares shift as the pawn moves: for the e4 pawn, the new key squares are d6, e6, and f6. White's king on e5 is now just one step from reaching d6, e6, or f6 — the next set of key squares.

Key SquaresPassed Pawn
Alternative Moves
Kd5 — Kd5 also wins (stays on a key square) but is slower. The pawn advance is more efficient because it advances the position while maintaining key square control.
Kf4 — Draws! Stepping off the key squares (d5, e5, f5) gives up the winning advantage. The king must stay on or advance toward key squares.
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1. ..Kd7

Black steps to d7, the best defense. By moving to the d-file, Black tries to stay near the pawn's path while keeping options open. The key squares for White's e4 pawn are d6, e6, f6 — Black aims to prevent the white king from reaching any of them.

Key Squares
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2. Kf6

Reaching a key square! The king advances to f6, which is one of the three key squares for the e4 pawn (d6, e6, f6). From a key square, White can guarantee the pawn's promotion. Notice the pattern: the king moved from e5 (a key square for e3) to f6 (a key square for e4). As the pawn advances, the king must advance to the *new* key squares to maintain the winning advantage.

Key SquaresPiece Activity
Alternative Moves
Kd5 — Kd5 also wins but is slower (DTM increases by 4). Kf6 is the fastest because it immediately reaches a key square while also controlling e7.
e5 — Draws! Pushing the pawn too early shifts the key squares to d7/e7/f7, but the king on e5 can't reach those in time. Always advance the king to key squares BEFORE pushing the pawn.
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2. ..Kd8

Black retreats to d8. With the white king on f6 controlling e7, Black must guard against Kf7 which would control the promotion square e8. Retreating is the best resistance, but the key square advantage is decisive.

Key Squares
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3. Kf7

The white king reaches the 7th rank, directly controlling the promotion square e8. This is the payoff of the key squares strategy — once the king reached f6 (a key square), advancing to f7 was guaranteed. For the e4 pawn, the key squares on the next rank up are d7, e7, f7. The king has reached f7, securing the promotion path completely.

Key SquaresPiece Activity
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3. ..Kd7

Black returns to d7, trying to approach the pawn's path. But the white king on f7 controls e8 — the promotion square is sealed. Black cannot prevent the pawn march.

Key Squares
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4. e5

Now the pawn advances safely. With the king on f7 guarding e8, the pawn can push forward without fear. The king has already done the hard work of reaching the key squares — now the pawn follows.

Passed PawnKey Squares
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4. ..Kc6

Black tries to circle around to intercept the pawn from the side. But with the king on f7 and the pawn already on e5, it's too late — the pawn is too far advanced.

Passed Pawn
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5. e6

The pawn pushes to the 6th rank, just two squares from promotion. The white king on f7 continues to shield e8. This is the power of key squares: once the king reaches them, the pawn's march is unstoppable.

Passed PawnTablebase Win
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5. ..Kd6

Black approaches the pawn, but it's fully protected by the king on f7. The defender arrived too late — the key square advantage from the beginning made this outcome inevitable.

Passed Pawn
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6. e7

The pawn reaches the 7th rank — one square from becoming a queen. The white king on f7 directly guards e8, making promotion unstoppable.

Passed PawnTablebase Win
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6. ..Ke5

Black moves away, unable to prevent promotion. The pawn on e7 is shielded by the white king and will promote next move.

Passed Pawn
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7. e8=Q+

Promotion with check! The pawn becomes a queen on e8, delivering check. King and Queen vs King is an easy checkmate. The entire win stemmed from the starting advantage: the king on e5 occupied a key square for the e3 pawn. From there, it advanced to key squares for each successive pawn position (f6 for e4, f7 for e5), guaranteeing promotion at every stage.

Passed PawnTablebase WinKey Squares

Key Takeaways

  • Every passed pawn has key squares — three squares two ranks ahead of the pawn (for pawns below the 5th rank)
  • If the attacking king reaches a key square, promotion is guaranteed regardless of the defender's play
  • As the pawn advances, the key squares shift forward — the king must advance to the NEW key squares
  • Always advance the king to key squares BEFORE pushing the pawn — pushing too early can draw
  • Stepping off the key squares (e.g., retreating or moving sideways) can throw away a winning position

Summary

You've learned the concept of key squares — the critical squares that guarantee pawn promotion once occupied by the attacking king. The key squares for a pawn below the 5th rank are the three squares two ranks ahead of the pawn. As the pawn advances, the key squares shift forward, and the king must advance to the new key squares to maintain the winning advantage.

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