Chess960 tactic on b8 (d6·2)
c9-28509naming 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 2400 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 f4, rook b6, bishop d6, pawn b2 c2 h2 a4 c5.
Black: king a7, queen e4, rook g1, pawn d5 h5 f6.
9 white and 6 black pieces are on the board; the puzzle position arises after move 37.
The position in numbers
White are ahead by 5 points of material (22 against 17; 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 a7.
It is White to move on move 37, with 37 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 5 pawns, Black 3. Files fully open (no pawns of either colour): e, g — natural highways for the rooks and queen. Half-open for White: d, f.
The White king has 2 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
37. Bb8+ Ka8 38. Ra6+ Kb7 39. Ra7+ Kc6 40. Qc7#
Why it works
- Great move! bishop to b8 keeps the pressure (#3).
- Well found: rook to a6 (#2).
- Precise: rook to a7 is the top choice (#1).
- Best move. queen to c7 is exactly what the engine plays (#).
- The line ends in a forced mate in 4.
- If instead Ka8, then Ra6+ and you stay on top.
Move by move
- 37. Bb8+ — bishop to b8 with check
- Ka8 — king to a8
- 38. Ra6+ — rook to a6 with check
- Kb7 — king to b7
- 39. Ra7+ — rook to a7 with check
- Kc6 — king to c6
- 40. Qc7# — queen to c7 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.
Clearance
Clear your own piece out of the way — with tempo — for the decisive blow.
Clearance is about your own piece standing in the way of the decisive blow — so you move it aside, or even throw it away. The key is to clear with tempo: jump off with a check, a capture or a threat, giving the opponent no time to regroup. The telltale sign: you see a crushing queen or rook move, but one of your own pieces blocks the line or occupies the square. Do not cling to it — a clearance sacrifice usually costs less than a missed attack.
About this position
These pieces come from starting position #846.
SP-846 · RampartScout — King on the wing (b/g) with a knight on the rim (a/h) — the rarest family.
The king starts on b1, the rooks on a1 and d1, 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 f1 and g1; their long diagonals reach a6 and a7 once the e- and f-pawns step aside.
The pawn on b2, c2 is defended by the king alone — the same soft spot f2 is in the classical setup.
The setup belongs to the RampartScout family; read right to left it becomes position 116.
The engine's main line opens with e4, putting a pawn straight into the centre.
Morozov Balance Index: 65 of 100 — class B — balanced. Engine evaluation of the starting position: +22 centipawns for White (depth 47, 400 000 000 nodes).
Explore position #846Provenance
Mined from the project's engine self-play games.
Pack 015 · SP-846
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