Attack on the uncastled king: queen to a8 (b7·7)
c9-26892naming 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.
Uncastled king: the enemy king is stuck in the centre — punish it before it castles.
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.
An uncastled king in the centre is a standing target. Look for ways to open the central files and diagonals against it with checks and threats before it can shelter — every tempo the king spends in the middle is a chance for a combination.
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 e1, queen b7, rook a1 h1, bishop f4, knight b5, pawn a2 b2 g2 c3 g3 h4.
Black: king e8, rook f6 h8, bishop d6 d7, pawn a5 e7 f7 g7 h7.
12 white and 10 black pieces are on the board; the puzzle position arises after move 17.
The position in numbers
White are ahead by 10 points of material (31 against 21; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on e1, the black king on e8.
It is White to move on move 17, with 45 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 6 pawns, Black 5. Files fully open (no pawns of either colour): d — natural highways for the rooks and queen. Half-open for White: e, f.
Black hold the bishop pair, an edge in open lines. The White king has 7 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
17. Qa8+ Bb8 18. Qxb8+ Bc8 19. Qxc8#
Why it works
- Great move! queen to a8 keeps the pressure (#2).
- Spot on — queen to b8 (#1).
- Precise: queen to c8 is the top choice (#).
- The line ends in a forced mate in 3.
- If instead Bb8, then Qxb8+ and you win the bishop.
Move by move
- 17. Qa8+ — queen to a8 with check
- Bb8 — bishop to b8
- 18. Qxb8+ — queen to b8 (capture) with check
- Bc8 — bishop to c8
- 19. Qxc8# — queen to c8 (capture) 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.
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.
Counter-strike
Don't defend — answer the threat with a bigger one.
The counter-strike: instead of defending against the threat, you answer with a bigger threat of your own. While your opponent grabs a pawn, you deliver mate — the arithmetic favors you. Look for a counter when direct defenses fail: do you have a check, an attack on the queen, a mating threat? The beginner's error is meeting every threat with a reflexive defense without checking the counterattacking resources first.
About this position
These pieces come from starting position #692.
SP-692 · ThroneGuard — The king starts in the middle of the back rank, on d or e, and neither knight begins in a corner.
The king starts on e1, the rooks on a1 and h1, the queen on d1.
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.
The bishops stand on b1 and c1; their long diagonals reach h7 and h6 once the c- and d-pawns step aside.
One second-rank pawn starts with no defender at all: g2.
The setup belongs to the ThroneGuard family; read right to left it becomes position 462.
The engine's main line opens with c4.
Morozov Balance Index: 86 of 100 — class A — most balanced. Engine evaluation of the starting position: +15 centipawns for White (depth 50, 400 000 000 nodes).
Explore position #692Provenance
Mined from the project's engine self-play games.
Pack 012 · SP-692
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