Chess960 tactic on b7 (e4)
c9-09448naming 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.
A fork made possible by the Chess960 piece placement.
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.
A set-up fork needs one preparing move before the fork lands — a check that drives the king onto the forking square, or a capture that lines the targets up. Find the preparation first, then the fork it makes possible.
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 b1, queen e4, rook d1 e8, bishop h1, knight d4, pawn a2 c2 h2 b3 f4.
Black: king b8, queen f6, rook b6, bishop h6 c8, pawn a3 d6 b7 c7 h7.
11 white and 10 black pieces are on the board; the puzzle position arises after move 32.
The position in numbers
White are ahead by 5 points of material (30 against 25; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on b1, the black king on b8.
It is White to move on move 32, with 45 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 5 pawns, Black 5. Files fully open (no pawns of either colour): e, g — natural highways for the rooks and queen. Half-open for White: d.
Black hold the bishop pair, an edge in open lines. 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
32. Qxb7+ Rxb7 33. Nc6+ Ka8 34. Rxc8+ Rb8 35. Rxb8#
Why it works
- Great move! queen to b7 keeps the pressure (#3).
- Well found: knight to c6 (#2).
- Strong! rook to c8 is the sharp choice (#1).
- Great move! rook to b8 keeps the pressure (#).
- The line ends in a forced mate in 4.
- If instead Rxb7, then Nc6+ and you stay on top.
Move by move
- 32. Qxb7+ — queen to b7 (capture) with check
- Rxb7 — rook to b7 (capture)
- 33. Nc6+ — knight to c6 with check
- Ka8 — king to a8
- 34. Rxc8+ — rook to c8 (capture) with check
- Rb8 — rook to b8
- 35. Rxb8# — rook to b8 (capture) and it is checkmate
Types in this puzzle
Arabian mate
Rook and knight — the oldest mate: the rook strikes next to the cornered king.
The Arabian mate is the oldest named pattern: the king is driven into the corner and the rook mates right next to it, guarded by a knight. The geometry is exact: king on h8, rook striking from h7, knight on f6 both protecting the rook and covering g8. The knight is irreplaceable — only it can guard the rook at point-blank range and hold the escape square at once. Look for the pattern when your knight is anchored two steps from the enemy corner.
Setup fork
The random setup allows a fork that classical chess never sees.
A setup fork is a double attack that exists only because of the unusual starting squares — in classical chess these targets never stand side by side. Look for pairs of undefended pieces on your opponent's back rank and for squares from which a knight or pawn hits both at once. Such forks usually appear within the first moves, before the pieces disperse. In every new position, note right away which starting pieces are defended by no one.
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.
About this position
These pieces come from starting position #763.
SP-763 · RampartGuard — The king starts out on a wing file, b or g, with neither knight in a corner.
The king starts on b1, the rooks on a1 and f1, the queen on g1.
From b1 the king makes the longest journey Chess960 allows when castling short: five squares to g1.
A bishop starts in the corner on h1: it has a single diagonal, which the g-pawn unlocks, running out to a8.
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 RampartGuard family; read right to left it becomes position 385.
The engine's main line opens with g4.
Morozov Balance Index: 69 of 100 — class B — balanced. Engine evaluation of the starting position: +21 centipawns for White (depth 45, 400 000 000 nodes).
Explore position #763Provenance
Mined from the project's engine self-play games.
Pack 015 · SP-763
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