Deflection

Deflection is forcing a specific defending piece away from a square or line it needs to guard, by giving it something more urgent to deal with. The defender isn't tricked and isn't lured toward danger for its own sake — it's simply given a threat it cannot decline, and the cost of answering that threat is abandoning whatever it was protecting.

What makes deflection different from decoy

Deflection and decoy are close enough that they get mixed up constantly, and the honest distinction is about direction, not mechanism. Deflection pulls a defender AWAY from a square it's guarding — the piece ends up somewhere less relevant. Decoy pulls a piece TOWARD a specific square, usually because that exact square is dangerous for it to stand on (a fork, a discovered attack, a mating square). Both frequently use a sacrifice to force the move, and both rely on the target having no better legal option, but deflection cares about what the piece stops doing, while decoy cares about where the piece ends up.

Finding the piece worth deflecting

The search always starts with the thing you actually want — a square, a piece, a mating idea — and works backward to whichever single defender makes it impossible right now. Once you've identified that piece, ask what it would take to force it to move: a check only it can answer, an attack on something else it's also the sole defender of, or a capture it's obligated to make. If a forcing move exists that the defender genuinely cannot ignore, and answering it takes the piece off the square or line you need clear, you have a deflection.

The sacrifice doesn't have to pay for itself alone

A common hesitation with deflection is treating the sacrificed material as the whole cost of the plan and asking whether it's "worth it" in isolation. That's the wrong accounting. In the example above, White gives up a rook for a bishop on the first two moves — by itself, a fair trade at best — and the entire point only becomes visible once the follow-up capture is counted. Judge a deflecting sacrifice by the full sequence it enables, not by the first exchange on its own.

Why an overloaded piece is the easiest target

Deflection works best against a piece that already has two jobs, because a defender with only one responsibility can often just... do it, and ignore whatever you're offering elsewhere. A piece guarding two different things at once has no such luxury — forcing it to answer one duty automatically strips the other. Before looking for a deflecting sacrifice, it's worth asking which of the opponent's pieces is already stretched thin; that piece is almost always the correct target.

When deflection fails

The plan collapses the moment the "forced" move turns out not to be forced — if the defender has a second way to meet the threat that doesn't require moving off its post (a different block, a counter-threat of its own, or simply ignoring a lower-value sacrifice because losing the material is cheaper than losing the square), the sacrifice is just a sacrifice. Always verify the defending piece has no alternative before committing material to remove it.

Deflection, decoy, and overloading are close enough relatives that it's worth reading all three together — the underlying idea (a defender that can't do everything at once) is the same, and what differs is which end of the problem you're attacking from.