Chess960 tactic on e3 (f4)
c9-12223naming 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: a forcing sequence that ends the game — the king has no escape.
Mate in 4: a forced checkmate in four moves — every reply is covered.
Difficulty 2120 ShuffleRating — expert level — few solve it at first try.
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.
This is a forced mating attack. Start from the enemy king: which of its squares are already covered, and which move takes away the rest while keeping the king in check? Forcing moves — checks and captures — are what turn an attack into mate.
A mate in four is a longer forced net: each of your moves is a check or an irresistible threat, and the king is driven step by step to a square where it is finally trapped. Verify that the defender has exactly one reply at every branch.
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 a2, queen d3, rook e1 g8, bishop f4, pawn c2 f2 h2 e6.
Black: king c5, rook h5 a8, bishop f8, knight b3, pawn a4 h4 a5.
9 white and 8 black pieces are on the board; the puzzle position arises after move 38.
The position in numbers
White are ahead by 7 points of material (26 against 19; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on a2, the black king on c5.
It is White to move on move 38, with 61 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 4 pawns, Black 3. Files fully open (no pawns of either colour): b, d, g — natural highways for the rooks and queen. Half-open for White: a.
The White king has 3 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
38. Be3+ Nd4 39. Qxd4+ Kb5 40. c4+ Ka6 41. Qb6#
Why it works
- Best move. bishop to e3 is exactly what the engine plays (#3).
- Spot on — queen to d4 (#2).
- Precise: pawn to c4 is the top choice (#1).
- Best move. queen to b6 is exactly what the engine plays (#).
- The line ends in a forced mate in 4.
- If instead Nd4, then Qxd4+ and you win the knight.
Move by move
- 38. Be3+ — bishop to e3 with check
- Nd4 — knight to d4
- 39. Qxd4+ — queen to d4 (capture) with check
- Kb5 — king to b5
- 40. c4+ — pawn to c4 with check
- Ka6 — king to a6
- 41. Qb6# — queen to b6 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 4+
A long forced mating combination.
Mate in four or longer is a marathon of forcing moves where the grip must never loosen. The tools are the same: checks, double threats and sacrifices that deny the opponent a single free tempo. Do not juggle the whole tree at once — walk the main line all the way to mate first, then verify the side branches. If somewhere the defender finds one quiet move that holds, your very first move was wrong.
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.
About this position
These pieces come from starting position #682.
SP-682 · BastionGuard — Both knights begin inside the board while the king stands on c or f; a position and its mirror twin share this family.
The king starts on c1, the rooks on b1 and h1, the queen on a1.
The king already stands on c1, so castling long moves only the rook, from b1 to d1.
The bishops stand on e1 and f1; their long diagonals reach a5 and a6 once the d- and e-pawns step aside.
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 BastionGuard family; read right to left it becomes position 469.
The engine's main line opens with a4.
Morozov Balance Index: 43 of 100 — class C — noticeable edge. Engine evaluation of the starting position: +28 centipawns for White (depth 43, 400 000 000 nodes).
Explore position #682Provenance
Mined from the project's engine self-play games.
Pack 015 · SP-682
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