Exercise 5.1Mate in 2
White to move
Mate in 2.
5
Calculation in Chess · Yatish Chandra Shukla
Forcing Moves and Short Sequences
In this lesson you will learn
- How to link forcing moves into a sequence
- Why a line made only of forcing moves is easy to calculate
- Three classic ideas: decoy, deflection and removing the guard
- How to stop and judge the position at the end of a line
Every board on this page is live. Move the pieces by tapping or dragging, click any move in the lines to see that position, and press ↺ to start again.
5.1 Chains of Forcing Moves
So far most of our calculations have been one or two moves long. Real combinations are often longer: three, four, even five moves. That sounds difficult — but there is a secret. A long combination is usually built from moves that are all forcing. After each one, the opponent has only one or two sensible replies.
Think of it like a corridor rather than an open field. In an open field you could walk in any direction, and you would have to imagine all of them. In a corridor there is only one way to go. A line where every move is a check, a capture or a serious threat is a corridor: you can walk to the end of it in your head.
NoteCount the branches. If, after each of your moves, the opponent has only one or two replies, a four- move combination has only a handful of lines in total. If each move allows ten replies, even two moves deep is too much to calculate.
5.2 How to Calculate a Sequence
1. Start with the most forcing move. Checks first, then captures, then threats — the CCT order.
2. List every reply. After a check there are usually very few. Write them down, even the ones that look hopeless for your opponent.
3. Follow the main line, but come back for the others. It is easy to calculate the line you like and forget the side-lines. Tick off each reply only when you have an answer to it.
4. Stop at a quiet position and judge it. When the forcing moves run out, count the material, look at the kings, and run the CCT scan for your opponent one last time.
LessonA combination is only finished when every defence has been answered. The defence you did not look at is the one your opponent will play.
5.3 Three Classic Ideas
Most short combinations are built from a few simple ideas. Learning their names helps you recognise them on the board.
Decoy. You force an enemy piece — often the king or queen — onto a particular square, usually by offering a sacrifice there. Once it stands on that square, a fork, a pin or a mate becomes possible. In
Exercise 2.9 the rook check on g8 decoyed Black's rook to g8, where the f7 pawn captured it with mate.
Deflection. You force a defending piece to leave its post. The piece that guarded a square, a piece or the back rank is lured away, and what it was guarding falls. In Exercise 2.7 White's queen sacrifice on d8 deflected Black's rook from the back rank.
Removing the guard. You simply capture the defender. In Example 2.2, ♗xf6 took the knight that guarded h7, and at once ♕xh7# became a threat.
TipThese three ideas often combine. A sacrifice may deflect one defender and decoy the king at the same time. The names are less important than the habit of asking: which piece is doing an important job, and how can I stop it?
5.4 Worked Examples
Study each example as if it were a puzzle: cover the solution, calculate, and only then read on.
Diagram 5.1Black to move
Example 5.1
Black to move. Mate in 2.
Find the key move.
Solution. 1...♕xd4+ 2.♔h1 ♖xh5# — the rook on d4 was not defended. Checkmate.
White's other defences do not help:
1...♕xd4+ 2.♔f1 ♕f2# — Black mates.
Compare a natural alternative, 1...♖xh5?: after 1...♖xh5 2.♖d1 ♗xa3 Black is winning. That is far less than the key move achieves.
LessonLook for squares from which one piece attacks two targets at the same time — especially with check.
Diagram 5.2Black to move
Example 5.2
Black to move. Calculate the combination to the end.
Find the key move.
Solution. 1...♕h1+ 2.♔e2 ♗g4+ Black keeps a decisive advantage.
Compare a natural alternative, 1...♘g5?: after 1...♘g5 2.♕e2 ♘f3+ Black is clearly better. That is far less than the key move achieves.
LessonLook for squares from which one piece attacks two targets at the same time — especially with check.
Diagram 5.3Black to move
Example 5.3
Black to move. Calculate the combination to the end.
Find the key move.
Solution. 1...♕xe3 2.h3 ♕xf4 3.♖g4 ♕c1+ — the queen on e3 was not defended. Black wins the queen and a pawn and keeps a winning position.
White's other defences do not help:
1...♕xe3 2.a4 ♕xc3 3.♔f2 — Black is winning.
1...♕xe3 2.♖g5 ♖xh4 3.♖hg1 — Black is winning.
Compare a natural alternative, 1...♘c7?: after 1...♘c7 2.♕d3 ♖f5 Black is a little better. That is far less than the key move achieves.
LessonLook for squares from which one piece attacks two targets at the same time — especially with check.
Diagram 5.4White to move
Example 5.4
White to move. Calculate the combination to the end.
Find the key move.
Solution. 1.♘f7+ ♔c8 2.♘xh8 ♕f3 3.♘f7 — the knight attacks the king and the rook at the same time. White wins a rook.
Compare a natural alternative, 1.♖xg2?: after 1.♖xg2 dxe5 2.dxe5+ the position is about equal. That is far less than the key move achieves.
LessonLook for squares from which one piece attacks two targets at the same time — especially with check.
Diagram 5.5White to move
Example 5.5
White to move. Mate in 3.
Find the key move.
Solution. 1.c7+ ♖ab7 2.cxb8=♕+ ♗xb8 3.♕xb7# — moving the pawn uncovers a check from the bishop on f3. White gives up the queen to force mate.
Black's other defences do not help:
1.c7+ ♖bb7 2.♕h8# — White mates.
Compare a natural alternative, 1.fxg3?: after 1.fxg3 ♖xb2 2.c7+ White is winning. That is far less than the key move achieves.
LessonWhen a piece moves, look at what stands behind it. A discovered attack hits two things at once.
Diagram 5.6White to move
Example 5.6
White to move. Calculate the combination to the end.
Find the key move.
Solution. 1.♘xd5 ♖c6 2.♗e4 f5 3.♗b2 White wins a knight and keeps a winning position.
Black's other defences do not help:
1.♘xd5 ♕e6 2.♘hf6+ ♔h8 — White is winning.
1.♘xd5 ♖d8 2.♗b2 ♕e6 — White is winning.
Compare a natural alternative, 1.♗b2?: after 1.♗b2 ♕xc7 2.c4 Black is clearly better. That is far less than the key move achieves.
LessonMaterial can be given away when the result has been calculated to the end. Count at the end of the line, not after the first move.
Diagram 5.7White to move
Example 5.7
White to move. Calculate the combination to the end.
Find the key move.
Solution. 1.♕xh6 ♖f7 2.♖hg1 b5 3.cxb6 White wins two pawns and keeps a winning position.
Black's other defences do not help:
1.♕xh6 b5 2.♗d4 ♖f7 — White is winning.
1.♕xh6 ♖ac8 2.♖hg1 ♖f7 — White is winning.
Compare a natural alternative, 1.♕c3?: after 1.♕c3 hxg5 2.dxc6 Black is clearly better. That is far less than the key move achieves.
LessonMaterial can be given away when the result has been calculated to the end. Count at the end of the line, not after the first move.
Diagram 5.8White to move
Example 5.8
White to move. Calculate the combination to the end.
Find the key move.
Solution. 1.♘xd4 ♗b4+ 2.c3 O-O 3.♘f3 White wins a knight.
Black's other defences do not help:
1.♘xd4 ♗d6 2.♘b5 O-O — White is clearly better.
1.♘xd4 ♗d7 2.♗d2 O-O-O — White is clearly better.
Compare a natural alternative, 1.♕d1?: after 1.♕d1 ♘xf3+ 2.♕xf3 Black is a little better. That is far less than the key move achieves.
LessonMaterial can be given away when the result has been calculated to the end. Count at the end of the line, not after the first move.
Diagram 5.9Black to move
Example 5.9
Black to move. Calculate the combination to the end.
Find the key move.
Solution. 1...bxc3 2.g5 ♘xe4 3.♗xe4 dxe4 Black wins a bishop and a pawn.
White's other defences do not help:
1...bxc3 2.b4 ♗xb4 3.g5 — Black is winning.
1...bxc3 2.a4 cxb2 3.♖a2 — Black is winning.
Compare a natural alternative, 1...♘c6?: after 1...♘c6 2.♘xd5 ♘xd5 Black is a little better. That is far less than the key move achieves.
LessonMaterial can be given away when the result has been calculated to the end. Count at the end of the line, not after the first move.
Diagram 5.10White to move
Example 5.10
White to move. Calculate the combination to the end.
Find the key move.
Solution. 1.♖d1 ♕a6 2.♕xe5 ♗g4 3.♕c7 White wins a knight.
Black's other defences do not help:
1.♖d1 ♕xe3+ 2.♕xe3 gxf6 — White is clearly better.
1.♖d1 ♕c4 2.♖d4 ♕c5 — White is clearly better.
Compare a natural alternative, 1.h3?: after 1.h3 ♘c4 2.♖1f3 the position is about equal. That is far less than the key move achieves.
LessonMaterial can be given away when the result has been calculated to the end. Count at the end of the line, not after the first move.
Remember
- Long combinations are made of forcing moves, so they can be calculated like a corridor, not an open field.
- After each of your moves, list every reply and tick it off only when it is answered.
- Stop when the forcing moves run out, count the material, and scan for your opponent's counter- chances.
- Look for defenders with important jobs: decoy them, deflect them, or remove them.
Daily PracticeSolve two or three puzzles a day without moving the pieces. Write the whole line down, including the opponent's replies, before you check the answer. If your line is right but you missed a side-line, count it as wrong — that is how real games are lost.
Exercises · Lesson 5
These puzzles need two to four moves of calculation. Write down every forcing move and every reply. Remember: a combination works only if it works against all defences.
Exercise 5.2Find the move
Black to move
Black to move. Calculate the combination to the end.
Exercise 5.3Find the move
Black to move
Black to move. Calculate the combination to the end.
Exercise 5.4Find the move
Black to move
Black to move. Calculate the combination to the end.
Exercise 5.5Find the move
Black to move
Black to move. Calculate the combination to the end.
Exercise 5.6Find the move
White to move
White to move. Calculate the combination to the end.
Exercise 5.7Find the move
White to move
White to move. Calculate the combination to the end.
Exercise 5.8Find the move
White to move
White to move. Calculate the combination to the end.
Exercise 5.9Find the move
Black to move
Black to move. Calculate the combination to the end.
Exercise 5.10Find the move
White to move
White to move. Calculate the combination to the end.
Exercise 5.11Find the move
White to move
White to move. Calculate the combination to the end.
Exercise 5.12Find the move
White to move
White to move. Calculate the combination to the end.
Exercise 5.13Find the move
White to move
White to move. Calculate the combination to the end.
Exercise 5.14Find the move
Black to move
Black to move. Calculate the combination to the end.
Exercise 5.15Find the move
Black to move
Black to move. Calculate the combination to the end.
Exercise 5.16Find the move
Black to move
Black to move. Calculate the combination to the end.
Exercise 5.17Find the move
White to move
White to move. Calculate the combination to the end.
Exercise 5.18Find the move
White to move
White to move. Calculate the combination to the end.
Exercise 5.19Find the move
Black to move
Black to move. Calculate the combination to the end.
Exercise 5.20Find the move
White to move
White to move. Calculate the combination to the end.
Exercise 5.21Find the move
Black to move
Black to move. Calculate the combination to the end.
Exercise 5.22Find the move
Black to move
Black to move. Calculate the combination to the end.
Exercise 5.23Find the move
Black to move
Black to move. Calculate the combination to the end.
Exercise 5.24Find the move
Black to move
Black to move. Calculate the combination to the end.
Exercise 5.25Find the move
Black to move
Black to move. Calculate the combination to the end.
Exercise 5.26Find the move
White to move
White to move. Calculate the combination to the end.
Exercise 5.27Mate in 4
White to move
Mate in 4.
Exercise 5.28Mate in 4
White to move
Mate in 4.
Exercise 5.29Find the move
Black to move
Black to move. Calculate the combination to the end.
Exercise 5.30Find the move
White to move
White to move. Calculate the combination to the end.