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The Trebuchet

Learn the trebuchet — a critical pawn endgame pattern where the side that pushes their pawn first wins the race to promotion.

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Introduction

The trebuchet is one of the most important patterns in King and Pawn endgames. It's a mutual zugzwang position where whoever gets to push their pawn first wins — and moving the king instead draws or loses. In this position, both sides have a passed pawn needing three squares to promote. White has a b5 pawn, Black has an e4 pawn. The kings stand near the opponent's pawn. The critical insight: push the pawn immediately! If White plays b6 first, the b-pawn promotes before Black's e-pawn. If it were Black's turn, Black would play e3 and win instead. In the trebuchet, a single tempo decides everything.

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1. b6

Push the pawn! This is the only winning move. White advances the b-pawn immediately, starting the race to promotion. The b-pawn reaches b8 in two more moves, while Black's e-pawn needs three moves to reach e1. Every king move draws or is slower. For example, Kd4 draws because it wastes a tempo — Black would then push e3 and the pawn race becomes equal. In the trebuchet, the pawn move is everything.

ZugzwangCourse de pions
Coups alternatifs
Kd4Draws! Moving the king wastes the crucial tempo. Black plays e3 and the pawn race is level.
Kxe4Draws! Capturing the pawn gives White a KP vs K position, but it takes too long to promote the b-pawn from here.
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1. ..e3

Black pushes the e-pawn in response — the best defense. Black starts their own race to promotion, hoping the e-pawn can queen or at least create enough counter-play. But White got to push first, so White's pawn is one tempo ahead.

Course de pionsPion passé
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2. b7

The b-pawn advances to the 7th rank — one square from promotion. White is ahead in the race: the b-pawn will queen next move, while Black's e-pawn is only on e3.

Course de pionsPion passé
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2. ..Kc3

Black moves the king toward the center rather than just pushing the e-pawn. Both Kc3 and e2 delay equally (same DTM). The king heads toward the queenside to potentially interfere, but the b-pawn promotes next move regardless.

Course de pions
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3. b8=Q

Promotion! The b-pawn becomes a queen. White now has a queen against Black's king and e-pawn. The race is won — White promoted first. Now the task is to use the queen to stop Black's e-pawn from promoting and force checkmate.

Pion passéGain par tablebases
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3. ..e2

Black pushes the e-pawn to e2, one square from promotion. This pawn is dangerous — if White is careless, Black could promote too and the game might be drawn. The queen must stop this pawn efficiently.

Pion passéCourse de pions
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4. Qb1

The queen drops to b1, aiming diagonally at the e-pawn's promotion square. From b1, the queen controls the entire b1-f5 diagonal and the first rank, keeping the e-pawn under watch while preparing to harass the black king.

Activité des piècesMenace
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4. ..Kd2

Black's king shields the e2 pawn, trying to support its advance to e1. This is the best defense — keeping the king near the pawn.

Pion passé
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5. Qb4+

Check! The queen delivers check from b4, forcing the black king away from the e2 pawn. This is the standard technique against a passed pawn: use checks to drive the king away, then capture or blockade the pawn.

Activité des piècesMenace
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5. ..Kd1

Black retreats to d1, staying as close to the pawn as possible. The king still defends e2 from d1.

Pion passé
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6. Qd4+

Another check, driving the king to the c-file. Each check pushes the king further from the e2 pawn, making it harder to protect.

Activité des piècesMenace
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6. ..Kc1

Black moves to c1. The king is being pushed sideways, away from the e-pawn. Black's defensive task is becoming increasingly difficult.

Pion passé
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7. Qe3+

Check from e3, forcing the king back toward d1. The queen systematically restricts Black's options while staying near the e2 pawn.

Activité des piècesMenace
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7. ..Kd1

Black returns to d1, the only square that keeps the king near the pawn. The repetition shows how limited Black's options are.

Zugzwang
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8. Qd3+

Check on d3, forcing the king to the e-file. This is the key preparatory check — after the king moves to e1, White's king can begin marching in.

Activité des piècesMenace
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8. ..Ke1

Black's king goes to e1, directly defending the e2 pawn. But now the king is on the edge of the board with fewer escape squares.

Zugzwang
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9. Ke4

Now the white king marches in! With the black king pinned down defending e2, White's king approaches to create a decisive mating net. The queen controls the key lines while the king closes the distance.

Activité des piècesCases clés
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9. ..Kf2

Black tries to escape sideways with the king, but the pawn on e2 is now less defended. The king and pawn are getting separated.

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10. Qf3+

Check on f3, driving the king back to e1. The queen and king work in tandem — the queen restricts while the king approaches.

Activité des piècesMenace
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10. ..Ke1

Black returns to e1. The king is running out of squares — it must stay near e2 but keeps getting pushed back.

Zugzwang
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11. Kd3

The white king reaches d3 — right next to the e2 pawn. Now White threatens to capture the pawn directly. Black is in complete zugzwang: every possible move makes things worse.

ZugzwangCases clés
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11. ..Kd1

Black's only legal move. The king steps to d1, but now the queen can capture the pawn with check.

Zugzwang
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12. Qxe2+

The queen captures the e2 pawn with check. Black's last hope is gone. The position is now a simple King and Queen checkmate.

Gain par tablebases
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12. ..Kc1

Black's only legal move. The king retreats to the corner, but checkmate is unavoidable.

Gain par tablebases
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13. Qc2#

Checkmate! The queen delivers mate on c2. The entire game was decided on move 1: White pushed the b-pawn first, winning the tempo battle that defines the trebuchet. If it had been Black's turn in the starting position, Black would play e3 and win instead — the trebuchet is a mutual zugzwang where the side that pushes first wins.

ZugzwangGain par tablebases

Points clés

  • In a trebuchet, push the pawn immediately — moving the king wastes the decisive tempo
  • The trebuchet is a mutual zugzwang: whoever moves first wins by pushing their pawn
  • A single tempo (one move) can decide the entire game in pawn endgames
  • After promoting first, use your queen to check the king away from the enemy pawn
  • Bring your king in once the queen has the opponent's king tied down defending the pawn

Résumé

You've learned the trebuchet — a mutual zugzwang in pawn endgames where the side that pushes their pawn first wins the race to promotion. In the starting position, both pawns needed three moves to promote, but White got to go first with b6. After promoting to a queen, White used a systematic checking technique to drive the black king away from the e-pawn, brought the king in to support, and delivered checkmate.

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