Mate in 3: rook to a1 (f1)
c9-28469naming 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 b2, queen e7, rook f1, bishop e4, pawn h2 c3 b4 d6.
Black: king a7, queen b6, rook b8 h8, bishop h6, knight e2, pawn b5 c7 f7 h7.
8 white and 10 black pieces are on the board; the puzzle position arises after move 24.
The position in numbers
Black are ahead by 8 points of material (21 against 29; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on b2, the black king on a7.
It is White to move on move 24, with 48 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 4 pawns, Black 4. Files fully open (no pawns of either colour): a, e, g — natural highways for the rooks and queen. Half-open for White: f.
The White king has 6 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
24. Ra1+ Qa5 25. Rxa5+ Kb6 26. Qxc7#
Why it works
- Best move. rook to a1 is exactly what the engine plays (#2).
- Spot on — rook to a5 (#1).
- Precise: queen to c7 is the top choice (#).
- The line ends in a forced mate in 3.
- If instead Qa5, then Rxa5+ and you win the queen.
Move by move
- 24. Ra1+ — rook to a1 with check
- Qa5 — queen to a5
- 25. Rxa5+ — rook to a5 (capture) with check
- Kb6 — king to b6
- 26. Qxc7# — queen to c7 (capture) and it is checkmate
Types in this puzzle
Supported queen mate
The queen delivers mate face to face, protected by a friend.
The supported queen mate is the most common pattern of all: the queen lands next to the king and mates because a friendly piece or pawn protects her. The king is helpless — capturing is impossible, and the queen covers every neighboring square herself. Hunt for a protected square beside the enemy king: a knight, bishop or pawn eyeing it turns her invasion into mate. Verify one thing — that the square really is defended, or the king eats her.
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.
Royal fork
A fork with check: the king must move, and the second piece is lost.
A royal fork is a fork with check — one of the two targets is the king itself. The check must be answered first, so nobody is left to rescue the second piece. Look for squares where your piece gives check and simultaneously attacks an undefended queen or rook. It is the most reliable fork of all, because your opponent literally has no choice.
About this position
These pieces come from starting position #722.
SP-722 · BastionGuard — A c- or f-file king and two knights on inner files (b–g).
The king starts on c1, the rooks on b1 and h1, the queen on e1.
The king already stands on c1, so castling long moves only the rook, from b1 to d1.
A bishop starts in the corner on a1: it has a single diagonal, which the b-pawn unlocks, running out to h8.
One second-rank pawn starts with no defender at all: a2.
The setup belongs to the BastionGuard family; read right to left it becomes position 423.
The engine's main line opens with b4.
Morozov Balance Index: 51 of 100 — class B — balanced. Engine evaluation of the starting position: +26 centipawns for White (depth 43, 400 000 000 nodes).
Explore position #722Provenance
Mined from the project's engine self-play games.
Pack 013 · SP-722
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