Bishop first
The Ruy Lopez: out before the ark closes
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7…exd4. The notes are on the highlighted moves.
Other moves here
Lesson 4 of 4
BeginnerDon't Let Your Bishop Get Trapped
A bishop on b5 is an active piece, but Black's queenside pawns can chase it until it has nowhere left to go. Know when to trade it, and keep an escape route.
A piece is trapped when it has no safe square to go to. In the opening this happens most often to a bishop that has gone forward early: pawns attack it, it retreats, and the pawns follow until the last square is taken away.
White's bishop on b5 in the Ruy Lopez is the classic victim. After …a6 and …b5 it sits on b3, and if Black can also play …c5 and …c4, it is shut in for good: the Noah's Ark Trap. In the Rossolimo Sicilian the same pawns are already halfway there, so the bishop has to be traded at once. And in the Mortimer Trap, chasing the bishop away leaves a knight without a defender.
This lesson is taught from White's side, with exercises from Black's side of the traps. A move that works keeps the position; a move that fails loses (see "How these lessons were checked"). You get three conditions, each with a move that works and one that fails, the right way move by move, and four positions to solve.
The idea
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hThe ark
After 8.Qxd4?? c5 9.Qd5 Be6 10.Qc6+ Bd7 11.Qd5 c4 the pawns on a6, b5 and c4 surround the bishop on b3. It cannot escape, and Black wins it.
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hHalfway there
In the Rossolimo Sicilian Black's c-pawn is already on c5. If the bishop retreats to a4, …b5 and …c4 trap it at once.
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hChased away
In the Mortimer Trap, 5…c6! attacks the bishop on b5. When it moves, …Qa5+ forks the king and the knight on e5.
Before you play it: the checklist
Each condition with two positions: one where it holds and the move works, one where it is missing and the same move fails. The number is Stockfish's evaluation after the move, from the attacker's side.
1.Keep the bishop's escape route
When the pawns are closing in, move the bishop out while there is still a square for it.
It works
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h8.Bd5−0.1
8.Bd5 gets the bishop out before …c5 and …c4, and the position is level.
The engine prefers c3 (0.0).
It fails
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h8.Qxd4−4.6
8.Qxd4?? takes the pawn, but 8…c5! and …c4 trap the bishop.
The engine prefers c3 (0.0).
2.Trade it before it is trapped
If retreating walks into the pawns, trade the bishop for a knight instead.
It works
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h4.Bxc6+0.7
4.Bxc6 trades the bishop and doubles Black's pawns.
It fails
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h4.Ba4−4.3
4.Ba4?? keeps the bishop, but 4…b5 5.Bb3 c4 traps it.
The engine prefers Bxc6 (+0.5).
3.A chased bishop leaves something behind
Before you grab, ask what happens when your bishop is attacked and has to move.
It works
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h5.Bc4+0.4
5.Bc4 takes the bishop out of the pawns' way, and White is slightly better.
The engine prefers Nc3 (+0.2).
It fails
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h5.Nxe5−2.3
5.Nxe5? takes the pawn, but 5…c6! hits the bishop, and when it moves …Qa5+ forks the king and knight.
The engine prefers Nc3 (+0.2).
Move by move
Click a move or use the arrows. Under each note you'll find the defender's other choices and how to answer them. The number under the board is Stockfish's evaluation from the attacker's side.
8621abcdehBishop for knight
The Rossolimo: trade at once
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3…a6. The notes are on the highlighted moves.
Other moves here
Your turn
Each position has one best move. Find it, then check the solution.
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aExercise 1
Black to move. White's queen has taken the pawn on d4.
Show solution
8...c5
8…c5! attacks the queen, and …c4 will follow: the bishop on b3 is trapped.
The Noah's Ark Trap.
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aExercise 2
Black to move. White's bishop has retreated to b3.
Show solution
5...c4
5…c4 shuts the bishop in: the pawns on a6, b5 and c4 take away every square.
The Noah's Ark Trap in the Sicilian.
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aExercise 3
Black to move. White has taken the pawn on e5.
Show solution
5...c6
5…c6! attacks the bishop. When it moves, …Qa5+ forks the king and the knight on e5.
The Mortimer Trap.
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aExercise 4
Black to move. White's bishop has retreated to a4.
Show solution
6...Qa5+
6…Qa5+ checks the king and attacks the knight on e5, and Black wins a piece.
The Mortimer Trap.
From history
Noah and Mortimer
The origin of the name Noah's Ark is uncertain: the pawns on a6, b5 and c4 may look like an ark, or the trap may be "as old as Noah's Ark". Even masters have fallen for it: Steiner lost his bishop to Capablanca this way at Budapest in 1929, in a line Alekhine had recommended. The Mortimer Trap is named after James Mortimer, who played his defence at London 1883 and lost all three games.
Take these into your games
Count the escape squares
A piece with no safe square is in danger. Watch the squares your bishop can retreat to.
Pawns trap pieces
Advancing pawns take squares away. Several in a row can shut a piece in completely.
Trade before it is too late
If the bishop is about to be trapped, trading it for a knight is often the best choice.
A retreat can leave a piece loose
When a piece is chased away, check what it was guarding.
Do not grab while the bishop is in danger
Taking a pawn costs time, and time is what the pawns need to close the trap.