A discovered attack happens when a piece moves and, in doing so, unmasks the attack of another piece that was hiding behind it on a rank, file, or diagonal. The piece that moves can create a threat of its own too, or simply step aside; either way, it’s the unmasked piece that strikes.

How it works

The knight steps off the e-file: the white rook, hidden until now, checks the black king.

Before the move, White’s knight is blocking its own rook on the e-file. By playing Nc5, the knight moves to a new square without itself touching the black king, but it clears the file, and the rook that was waiting behind it delivers check immediately. That’s the whole power of a discovery: the player gains a “free” attacking tempo, since the piece that moves can make itself useful elsewhere while the unmasked piece does the striking.

The special case of discovered check

When the unmasked piece delivers check, it’s called a discovered check. It’s a fearsome weapon: the enemy king must deal with the check first, which leaves the piece that just moved completely free: it can capture a piece, attack another one, or even give check itself on top of it (that special case is called a double check).

Creating and defending against a discovered attack

To create a discovery, look for one of your pieces lined up in front of another piece (often a rook, bishop, or queen), and aim for a square where stepping aside unmasks a profitable attack: a check, a capture, or a double threat.

To defend against one, stay alert whenever an enemy piece is lined up with your king or a valuable piece, even if another piece currently seems to block the line; that piece can step aside at any moment. Keep your king away from open alignments with enemy rooks, bishops, or queens, especially when an enemy piece currently sits between the two.

Frequently asked questions

What’s the difference between a discovered attack and a pin?

A pin immobilizes a piece because moving it would expose a more valuable piece. A discovered attack is the opposite: it’s precisely by moving a piece that you reveal an attack, often to great benefit.

Why is discovered check so dangerous?

Because the piece that moves has no constraints: it doesn’t need to give check itself, so it’s free to capture a piece, threaten the king a second time, or set up a mate, while the opponent is forced to respond to the check.

Can every piece produce a discovery?

Yes, as long as a long-range piece (rook, bishop, or queen) is lined up behind it. Any piece can play the role of the one that steps aside (knight, bishop, pawn, or even the king), as long as it clears the attacking line at the right moment.