Mate in 3: knight to b5 (c7)
c9-26518naming tag (square·N)Opens in the app if installed, otherwise downloads the APK.
The tactical motive
Chess960 twist: use the unusual starting setup of the pieces.
Mate in 3: a forced sequence that ends in checkmate.
Difficulty 1630 ShuffleRating — for advanced tacticians.
White to move — find the best continuation
How to recognize this tactic
In Chess960 the pieces start on unfamiliar squares, so tactics appear earlier and from unusual angles. Do not trust classical patterns — read the actual lines of the bishops, the rooks and the queen from where they really stand in this position.
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.
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 c3, rook d7, bishop f4, knight c7, pawn a2 e2 g3 h3 b4 c5 g5.
Black: king a7, rook c6, pawn a3 b5.
11 white and 4 black pieces are on the board; the puzzle position arises after move 37.
The position in numbers
White are ahead by 11 points of material (18 against 7; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on c3, the black king on a7.
It is White to move on move 37, with 32 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 7 pawns, Black 2. Files fully open (no pawns of either colour): d, f — natural highways for the rooks and queen.
The White king has 5 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
37. Nxb5+ Ka6 38. Ra7+ Kxb5 39. Ra5#
Why it works
- Best move. knight to b5 is exactly what the engine plays (#2).
- Spot on — rook to a7 (#1).
- Precise: rook to a5 is the top choice (#).
- The line ends in a forced mate in 3.
- If instead Ka6, then Ra7+ and you stay on top.
Move by move
- 37. Nxb5+ — knight to b5 (capture) with check
- Ka6 — king to a6
- 38. Ra7+ — rook to a7 with check
- Kxb5 — king to b5 (capture)
- 39. Ra5# — rook to a5 and it is checkmate
Types in this puzzle
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.
Sacrifice attack
Give up material to unleash a decisive attack.
A sacrificial attack gives up material on purpose to rip the king's shelter open and launch a decisive assault. The sac is sound when you get concrete assets in return: open lines to the king, tempi, pieces ready to pour in. The signs: a poorly sheltered king, your forces aimed at its home, defenders stranded far away. The iron rule is to calculate, not hope — once the material is gone, there is no way back.
Endgame tactic
Tactics live in the endgame too — strike while material is scarce.
Tactics do not retire when the queens come off: forks, pins and double attacks live on in the endgame. With so little material left, every tactical loss is almost always decisive. The signs are the usual ones — undefended pieces, king and piece on one line, a pawn about to promote. Even in a "technical" ending, scan for a shot before every move, both yours and your opponent's.
About this position
These pieces come from starting position #591.
SP-591 · ThroneGuard — Both knights start on inner files (b–g) while the king sits centrally on d or e — one of 204 positions filed here.
The king starts on d1, the rooks on b1 and e1, the queen on a1.
Castling ends where it always does: king to g1 and rook to f1 on the short side, king to c1 and rook to d1 on the long one.
A bishop starts in the corner on h1: it has a single diagonal, which the g-pawn unlocks, running out to a8.
The pawn on c2 is defended by the king alone — the same soft spot f2 is in the classical setup.
The setup belongs to the ThroneGuard family; read right to left it becomes position 272.
The engine's main line opens with b4.
Morozov Balance Index: 2 of 100 — class D — largest edge. Engine evaluation of the starting position: +54 centipawns for White (depth 41, 400 000 000 nodes).
Explore position #591Provenance
Mined from the project's engine self-play games.
Pack 012 · SP-591
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