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Discovered attack

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abcdefgh
8
e8 black queen
e5 black king
e4 white bishop
e3 white rook
g3 black rook
b2 white king
g2 white pawn
8
77
66
55
44
33
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abcdefgh
From this position, 1.Bf3+ is a winning discovered check that skewers the black king and queen

In chess, a discovered attack is a direct attack revealed when one piece moves out of the way of another.[1] Discovered attacks can be extremely powerful, as the piece moved can make a threat independently of the piece it reveals. Like many chess tactics, they often succeed because the opponent would be unable to meet two threats at once unless one of the attacked pieces can simultaneously move away from its own attack and capture the other attacking piece. While typically the consequence of a discovered attack is the gain of material, they do not have to do this to be effective; the tactic can be used merely to gain a tempo.[2] If the discovered attack is a check, it is called a discovered check.

Types

abcdefgh
8
a8 black rook
c8 black queen
e8 black rook
g8 black king
b7 black bishop
g7 black bishop
h7 black pawn
e6 white knight
g6 black pawn
h6 black knight
a5 black pawn
c5 black pawn
b4 black pawn
e4 black pawn
f4 white pawn
b3 white queen
e3 white pawn
g3 white pawn
h3 white bishop
a2 white pawn
b2 white pawn
b1 white king
c1 white rook
8
77
66
55
44
33
22
11
abcdefgh
The move 1.Nc7+, besides forking both rooks with the knight, also reveals an attack on Black's queen and a check.
abcdefgh
8
h6 black king
g5 black pawn
h5 white pawn
f4 white bishop
h4 white rook
h1 white king
8
77
66
55
44
33
22
11
abcdefgh
Position after 1...g7–g5. An en passant capture can reveal two checks at once.

When the moving piece gives check to the opponent's king, the maneuver is often described as a discovered attack with check. When the discovered attack is itself a check, it is called a discovered check. If both pieces give check, a double check results.

Discovered attacks—especially checks—can win material when the moving piece captures an opposing piece nominally protected by another opposing piece. If the opponent deals with the discovered attack (obligatory if it is a check), the attacking player will have time to return the moving piece out of harm's way. This scenario is often referred to as a discovered attack (or check) with capture. A discovered check can also win material if the moving piece ends up attacking another undefended piece. In this case, it would be impossible for the opponent first to capture the moving piece unless the king can capture.

When the moving piece moves to a square from which it threatens to inflict checkmate on the next move, the tactic is called a discovered attack with mate threat. A discovered checkmate itself is also possible.

Less often, a move may discover multiple attacks, as in the first diagram where the knight's departure opens two crisscrossing diagonals. And in exceptional circumstances, it is even possible for two checks to be revealed simultaneously. The only way for this to happen in orthodox chess is by way of an en passant capture. In the position shown in the second diagram, Black has just played 1...g7–g5. White replies 2.hxg6e.p.++. The result is a double check: One check is given by the rook, discovered by the capturing pawn's move; the other by the bishop, created by the captured pawn's removal. (The bishop’s check is not a discovered check, as the black pawn is captured and not moved.) Such a check is extremely rare in practical play, but it is sometimes found in problems.

Example

abcdefgh
8
a8 black rook
c8 black bishop
e8 black king
f8 black bishop
g8 black knight
h8 black rook
a7 black pawn
b7 black pawn
f7 black pawn
g7 black pawn
h7 black pawn
e6 black pawn
b5 black cross
d5 black pawn
e5 white pawn
d4 black queen
d3 white bishop
a2 white pawn
b2 white pawn
f2 white pawn
g2 white pawn
h2 white pawn
a1 white rook
b1 white knight
c1 white bishop
d1 white queen
e1 white king
h1 white rook
8
77
66
55
44
33
22
11
abcdefgh
Position after 8...Qxd4. White wins Black's queen using 9.Bb5+ (×), a discovered attack with check.

The diagram illustrates a trap in the Advance Variation of the French Defence, based on a discovered attack. If, after 1.e4 e6 2.d4 d5 3.e5 c5 4.c3 Nc6 5.Nf3 Qb6 6.Bd3 cxd4 7.cxd4, Black mistakenly attempts to win White's d-pawn with 7...Nxd4?? 8.Nxd4 Qxd4 (diagram), White can play 9.Bb5+, a discovered attack (White's bishop gets out of the way of White's queen) against Black's queen with check. Black must get out of check, then White can follow up with 10.Qxd4.

References

  1. ^ Discovered Attack Article at Chesscorner.com
  2. ^ More detailed tutorial at MarkLowery.net [dead link]

Further reading

  • Farnsworth, Ward. "Ward Farnworth's Predator at the Chessboard". Web Document. A Field Guide to Chess Tactics. Retrieved 17 December 2013.
  • Polgar, Susan; Truong, Paul (2006). "4. Discoveries". Chess Tactics for Champions. Random House. ISBN 978-0-8129-3671-1.
  • Yusupov, Artur (2008). "7 The discovered attack". Build Up Your Chess with Artur Yusupov The Fundamentals 1. Quality Chess. ISBN 978-1-906552-01-5.