Mate in 2: pawn to a7
c9-17157Opens in the app if installed, otherwise downloads the APK.
The tactical motive
Chess960 twist: use the unusual starting setup of the pieces.
Mate in 2: the first move creates an unstoppable threat, the second delivers mate.
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.
Mate in two usually opens with a forcing move — a check, a capture or an unstoppable threat — that strips the king of squares or defenders, so the follow-up mate becomes unavoidable. Look for the first move that leaves the opponent only losing replies.
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 c1, rook a1 f2, bishop a5, pawn g2 h2 b3 a4 a6 c6.
Black: king c8, rook e8, bishop d1, pawn e4 g5 h7.
10 white and 6 black pieces are on the board; the puzzle position arises after move 26.
The position in numbers
White are ahead by 8 points of material (19 against 11; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on c1, the black king on c8.
It is White to move on move 26, with 33 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 6 pawns, Black 3. Files fully open (no pawns of either colour): d, f — natural highways for the rooks and queen. Half-open for White: e.
The White king has 4 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
26. a7 Bxb3 27. a8=R#
Why it works
- Sensible development: pawn to a7.
- Spot on — pawn to a8 (#).
- The line ends in a forced mate in 2.
- If instead Bxb3, then a8=R# and it is mate.
Move by move
- 26. a7 — pawn to a7
- Bxb3 — bishop to b3 (capture)
- 27. a8=R# — pawn to a8 and it is checkmate
Types in this puzzle
Promotion mate
The pawn promotes — and the new piece mates on the spot.
In a promotion mate the pawn takes its final step and the newborn piece mates on the spot. Sometimes the hero is a knight rather than a queen — it checks from the promotion square in a way no queen can. The sign: the enemy king lingers near the promotion square while your pieces already control its escape routes. When counting pawn races, always check whether the promotion itself is mate — that gains you a full tempo in the evaluation.
Mate in 2
A forced checkmate in two moves.
Mate in two: your move, any reply, then the mating blow. Start with the most forcing first moves — checks and sacrifices that shrink the opponent's options to almost nothing. Against every single reply you must have a mate ready, so check them all without exception. The common failure is analyzing the pretty defense and forgetting the boring one.
Promotion race
Both sides push passers — win the race by a tempo.
A promotion race is a sprint between two passed pawns: both sides push toward the last rank, and victory goes to whoever queens first or queens with check. You will recognize it when both players have far-advanced passers that neither king can catch. Count the tempi literally, move by move, all the way to promotion. The classic mistake is spending a tempo on a "useful" move — in a race, almost any non-pawn move loses.
About this position
These pieces come from starting position #829.
SP-829 · RampartScout — A wing-file king (b or g) and at least one corner knight: the rarest of the six families, just 72 positions.
The king starts on b1, the rooks on a1 and f1, the queen on e1.
From b1 the king makes the longest journey Chess960 allows when castling short: five squares to g1.
The bishops stand on d1 and g1; their long diagonals reach h5 and a7 once the e- and f-pawns step aside.
One second-rank pawn starts with no defender at all: g2.
The setup belongs to the RampartScout family; read right to left it becomes position 136.
The engine's main line opens with f4.
Morozov Balance Index: 24 of 100 — class D — largest edge. Engine evaluation of the starting position: +35 centipawns for White (depth 47, 400 000 000 nodes).
Explore position #829Provenance
Mined from the project's engine self-play games.
Pack 012 · SP-829
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