Discovered Attack

Moving a Shielding Piece with Tempo to Unleash a Hidden Ranged Battery Behind It

A Discovered Attack is a two-piece ambush: a front piece steps off a file, rank, or diagonal to create a threat of its own, simultaneously unmasking a stationary Rook, Bishop, or Queen behind it. When either piece delivers check, the opponent loses a full tempo and cannot defend the second target.

Coach Otto: Whenever your own knight or bishop blocks your rook on an open file, Otto treats it like a cocked bowstring waiting for a forcing target!

Open Anatomical Board Examples & Move Lines

[ARCHETYPE] Discovered Attack (+8.55 Winning) — FEN: 6k1/ppp2ppp/8/q3N3/8/6PP/PP1P1P1K/4R3 w - - 0 1 · Nc6 h6 Nxa5
1. Nc6! — Steps off the e-file to attack Black’s a5 Queen while unmasking White’s e1 rook for a back-rank mate threat on e8!
[MASTERPIECE] Discovered Check Winning Central Queen (+11.63 Winning) — FEN: 2r3k1/pp3ppp/8/3q4/8/3B1PP1/PP3QKP/3R4 w - - 0 1 · Bxh7+ Kxh7 Rxd5
1. Bxh7+! — Discovered check reversed: the bishop vacates the d-file with check on h7, unmasking the d1 rook onto Black’s undefended d5 Queen!

Geometric Preconditions & Board Triggers

A battery exists: your stationary ranged piece is temporarily masked by one of your own mobile pieces along a line toward an enemy target.
At least one of the two resulting threats MUST be forcing (check, mate threat, or capture of a higher-value unit).
In a Discovered Check (rear piece checks), the front vanguard can move almost anywhere—even onto a guarded square—to snatch an enemy piece.

Defensive Antidotes & Calculation Pitfalls

Treat any opposing Rook/Bishop/Queen lined up with your King or loose Queen—even through two pieces—as an active tactical hazard.
Step your Queen or King off the masked line proactively before your opponent finds a forcing vanguard jump.
Check whether the moving vanguard piece can be captured in a way that simultaneously blocks or answers the rear threat.

FAQ

Which is stronger: a Discovered Attack where the front piece checks, or a Discovered Check where the rear piece checks?

Both win a full tempo! When the front piece checks (like 1. Bxh7+!), it can even sacrifice itself to clear the line for the rear piece to capture a Queen; when the rear piece gives Discovered Check, the front piece enjoys near-total freedom to capture loose material.

How does Petrov’s Defense illustrate an early opening Discovered Check?

After 1.e4 e5 2.Nf3 Nf6 3.Nxe5 Nxe4?? 4.Qe2 Nf6??, White’s 5.Nc6+! unleashes a discovered check from Qe2 to Ke8 while the knight captures Black’s Queen on d8.

What happens when BOTH the moving vanguard and the unmasked rear piece give check?

That creates a Double Check (see T06)—the most forcing tactical blow in chess, against which only a King move is legal.

Sister Patterns, Opening Habitats & Grandmaster Links

T06 · Double Check (Unstoppable Simultaneous Check Along Two Intersecting Vectors Forcing King Flight) · T17 · Windmill (Relentless Seesaw Machine Alternating Direct Rook Checks and Discovered Bishop Checks) · T01 · Fork (Simultaneous Single-Piece Double Attack on Two High-Value Targets)