TacticsPlay as white

Calculate the Line

List the forcing moves, follow one candidate to its end, and verify the final position before you move.

Introduction

Strong players do not calculate further than you — they calculate fewer moves, in a fixed order. First list every forcing move: the checks, the captures, the threats. Then take one candidate and follow it reply by reply, three moves deep or until your opponent has no forcing answer left. Last, look at the position at the end of the line and ask what it actually is: a checkmate, a won piece, or nothing. Every position in this lesson is solved that way, and the test afterwards is played without hints, so make the method the habit.

Lesson Content

Try this position

Calculation starts with a list, not a move. Checks, captures and threats are the forcing moves — the ones that limit what your opponent can reply — so collect them first. Here White has two checks, Qxg7+ and Rxh7+, and one more capture, Qxb6. Then test each one: Qxg7+ Rxg7 hands over the queen for a rook, and Qxb6 axb6 hands it over for a pawn — both lose. That leaves the rook sacrifice Rxh7+, which is a candidate, not yet a decision: a sacrifice only becomes playable once the line behind it has been seen to the end.

ThreatSacrifice

Try this position

1. ..Rxh7+

Force checkmate: list every check first, then follow the most forcing one until you can see the final position.

Rxh7+ gives up the rook to drag the king into the open, and Kxh7 is the one legal reply — the rook on g7 cannot take, because the queen on f6 stands behind it on the diagonal to h8. Then Qh4+ leaves the king a single square, Kg6, and Rf6# is checkmate: the rook covers f5 and f7, the queen covers g5, h5, h6 and h7 and guards the rook, and the king has nowhere left.

ThreatSacrificeMating NetKing Attack

Alternative Moves

Qxg7+ — Qxg7+ Rxg7 trades the queen for a rook and ends the attack — Black is a queen for a rook ahead, and it is White's king that gets mated.

Qxb6 — Qxb6 axb6 gives up the queen for a pawn: White is a queen down, and the mating attack is gone with it.

Try this position

The second habit: see three moves deep before you choose between candidates. White has four checks — Qh7+, Qh8+, Bf7+ and Bh7+. One drops out at once: Qh8+ Kxh8 loses the queen for nothing. The other three all look alike, and only one of them mates, so a glance will not tell them apart. Take each in turn: find Black's reply, then ask whether White has another check, and whether that check leaves the king fewer squares or more. A line that runs out of checks with the king still breathing is a draw at best; play only the one that ends in a position you have actually seen to be mate.

ThreatMating Net

Try this position

2. ..Qh7+

Four checks are on offer — calculate each one to its end, and play only the one whose final position you have actually seen.

Qh7+ is the check that keeps forcing: Kf8 is the only legal reply, because the bishop on g6 covers h7 and f7. Qh8+ then leaves the king a single square, e7, and Qe8# is checkmate — the bishop on g6 guards the queen and f7, while the pawn on e5 takes d6 and f6 from the king.

ThreatMating NetKing Attack

Alternative Moves

Qh8+ — Qh8+ Kxh8 and the queen is gone for nothing — White is a queen down with no attack left.

Bf7+ — Bf7+ Kf8 and the follow-up Qh8+ runs into Kxf7, so the bishop has to go back to g6 with nothing to show: the mate is gone and the game is level.

Bh7+ — Bh7+ Kf8 and there is no second check that improves anything: White can repeat checks but never mates, and the game is a draw.

Try this position

The third habit: verify the end of the line before you play its first move. White has exactly one check, Qxf6+, and it costs the queen. Rd8 threatens the rook on f8 but is not a check, so Black would get a free move — and Black's queen on c1 is waiting for exactly that to start checking the white king. So follow the queen sacrifice until Black has no forcing answer left, then stop and look at the final position instead of trusting it. Is the king in check? Which of its squares — g8, g7, h7 — is still free? Can any black piece, the queen on c1 included, capture the checking piece or block? Only when every answer is no is the queen sacrifice a decision rather than a hope.

ThreatSacrificeMating Net

Try this position

3. ..Qxf6+

Force checkmate — and before you commit the first move, check every escape square in the final position.

Qxf6+ throws the queen in with check, and the line runs Rxf6 Rd8+ Rf8 Rxf8#: the rook checks along the back rank, g8 is covered by that rook, g7 by the pawn on h6, h7 is blocked by Black's own pawn, and the queen on c1 can neither capture the rook nor block, so it is checkmate. Black cannot decline either — if the king steps to g8 instead of taking, Qg7# mates at once, guarded by the pawn on h6.

ThreatSacrificeMating Net

Alternative Moves

Rd8 — Rd8 attacks the rook on f8 but gives no check, so Black gets a move: Qxh6+ takes the pawn that was covering g7, with check, and the mating net is gone — Black is winning.

Try this position

4. Rh2+

Force checkmate: Black must never get a free move, so calculate the whole sequence through to the end before you start.

Rh2+ starts a sequence in which every White move is a check, so Black never gets the free move that would save the game: Kg8 is the only legal reply, Nf6+ Kg7 keeps the king on the g-file (going to f8 instead only changes the order of the rook checks), Rh7+ Kf8 pushes it to the back rank, Rh8+ Ke7 sends it off again (g7 is the other option, and the rook mates on g8 then), and Re8# is checkmate — the knight guards the rook and d7, the pawn on e5 covers d6 and f6, and the king has no square. Five moves deep, and not one of them gave Black a choice that mattered.

ThreatMating NetKing Attack

Alternative Moves

Nf6+ — Nf6+ Kg7 and the knight has no second check, so Black gets a free move: Bc6 covers e8, the mating net is gone, and with the passed pawns on a3 and c3 Black is winning.

Try this position

Your turn to run the method on your own. White has three checks — Ra8+, Rh8+ and Rxf7+ — and the capture Rxh5. Calculate each check to its end: which first move wins material?

ThreatDeflectionSacrifice

Try this position

You have found a promising check and followed it three moves deep. What is the last thing to do before you play it?

Threat

Key Takeaways

Checks, captures, threats — list them all before you calculate any of them.
Follow one candidate reply by reply until your opponent has no forcing answer left, and notice how many of their replies were the only legal move.
Verify the final position: who is mated, what is won, and whether your opponent has a check or capture there.
A sacrifice is a candidate, not a decision, until the line behind it has been seen to the end.

Now play it through

Step through every move on a real board, try the wrong ones, and ask Knighty why they fail.

Practice Interactively

Related Lessons

Defensive Resources

Mate in Five

The Attack on f7

Summary

Long calculation is a procedure, not a gift. List the forcing moves — checks, captures, threats — then follow one candidate reply by reply until the opponent has no forcing answer left, and verify the final position before you commit. In this unit's test the hints are off the table: a solve that used a hint does not count, so run the whole method in your head before the first move.

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Practice Interactively

Next in this course

Mate in Four

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