Mate in 3: pin on b6
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The tactical motive
Mate in 3: a forced sequence that ends in checkmate.
Pin: a piece can't move without exposing something more valuable behind it.
Difficulty 1945 ShuffleRating — for advanced tacticians.
White to move — find the best continuation
How to recognize this tactic
In a mate in three every move must be forcing; the defender should never get a free tempo. Find the check or threat that herds the king, calculate the single defence to each, and confirm the net closes on the third move.
A pin freezes a piece in front of a more valuable one behind it. Scan the ranks, files and diagonals your bishop, rook or queen controls: if an enemy piece cannot move without exposing its king or queen, it is pinned and can be piled on or bypassed.
General method: before you move, list the forcing candidates — every check, every capture, every direct threat — and calculate those first. The solution to a tactic is almost always among them.
Position on the board
White: king g1, queen b3, rook a1 f1, bishop d5, knight c4, pawn b2 f2 g2 h2 c3 d3 e4 a5.
Black: king a7, queen f6, rook b8 h8, bishop d7, knight e7, pawn e5 a6 d6 h6 b7 c7 f7 g7.
14 white and 14 black pieces are on the board; the puzzle position arises after move 18.
The position in numbers
Material is level — 33 points of pieces on each side (pawn = 1, knight and bishop = 3, rook = 5, queen = 9).
The white king stands on g1, the black king on a7.
It is White to move on move 18, with 38 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 8 pawns, Black 8. No file is fully open, so the heavy pieces have to be pried in.
The White king has 1 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
18. Qb6+ cxb6 19. axb6+ Ka8 20. Rxa6#
Why it works
- Great move! queen to b6 keeps the pressure (#2).
- Well found: pawn to b6 (#1).
- Strong! rook to a6 is the sharp choice (#).
- The line ends in a forced mate in 3.
- If instead cxb6, then axb6+ and you stay on top.
Move by move
- 18. Qb6+ — queen to b6 with check
- cxb6 — pawn to b6 (capture)
- 19. axb6+ — pawn to b6 (capture) with check
- Ka8 — king to a8
- 20. Rxa6# — rook to a6 (capture) and it is checkmate
Types in this puzzle
Corner mate
Driven into the corner, the king runs out of squares.
The corner mate catches a king driven into the corner, where it has only three neighboring squares — all of them taken away or blocked. The corner is the worst home for a king, because the attacker needs to control the fewest squares there. Herd the king toward the corner with checks and never let it slip back toward the center. Cut off the escape routes before the final check, and the mate practically assembles itself.
Mate in 3
A forced checkmate in three moves.
Mate in three is a forced staircase: each of your moves narrows the opponent's choices, and the third one ends the game. Look for the start among checks and sacrifices — quiet first moves are rare in mating problems, but deliciously sneaky. Keep the tree in your head: every defense gets its own branch. Do not stop calculating after move two — see the final mating picture with your own eyes.
Win the pinned piece
The pinned piece cannot run — attack it again and win it.
A pinned piece cannot flee, which means you can win it outright by attacking it one more time. Count attackers against defenders: if you outnumber them, the piece is yours. The best extra attacker is a pawn, since it costs less than anything it might capture. Do not rush the capture — build up the pressure first, then harvest.
Provenance
Derived from the Lichess puzzle database (CC0).
Verified by Stockfish at depth 20+.
Solution forcedness confirmed (verified).
Pack 014
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