Chess960 tactic on b4 (b2)
c9-12474naming 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 2250 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 e1, queen e4, rook b1 g1, knight d2, pawn b2 c2 g3 h4 e5 e6.
Black: king c5, rook a4 g8, bishop h8, pawn f3 b6 g6.
11 white and 7 black pieces are on the board; the puzzle position arises after move 26.
The position in numbers
White are ahead by 12 points of material (28 against 16; 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 c5.
It is White to move on move 26, with 38 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 6 pawns, Black 3. Files fully open (no pawns of either colour): a, d — natural highways for the rooks and queen. Half-open for White: f.
The White king has 5 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
26. b4+ Rxb4 27. Qxb4+ Kc6 28. Qxb6+ Kd5 29. Qd6#
Why it works
- Great move! pawn to b4 keeps the pressure (#3).
- Spot on — queen to b4 (#2).
- Precise: queen to b6 is the top choice (#1).
- Best move. queen to d6 is exactly what the engine plays (#).
- The line ends in a forced mate in 4.
- If instead Rxb4, then Qxb4+ and you win the rook.
Move by move
- 26. b4+ — pawn to b4 with check
- Rxb4 — rook to b4 (capture)
- 27. Qxb4+ — queen to b4 (capture) with check
- Kc6 — king to c6
- 28. Qxb6+ — queen to b6 (capture) with check
- Kd5 — king to d5
- 29. Qd6# — queen to d6 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.
Remove the defender
Capture the guard first — then take what it protected.
Removing the defender is the straightforward plan: capture the guard first, then take what it guarded. Unlike deflection, the defender is not lured away — it is traded off or destroyed on the spot. Stare at the target you crave and ask who defends it, and whether that defender can be profitably eaten. Count the whole capture sequence, not just the first move — the trade must pay off at the end.
About this position
These pieces come from starting position #231.
SP-231 · ThroneScout — Centre-file king, rim knight: 204 of the 960 positions share this pattern.
The king starts on e1, the rooks on b1 and g1, 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.
A bishop starts in the corner on h1: it has a single diagonal, which the g-pawn unlocks, running out to a8.
One second-rank pawn starts with no defender at all: a2.
The setup belongs to the ThroneScout family; read right to left it becomes position 626.
The engine's main line opens with d4, putting a pawn straight into the centre.
Morozov Balance Index: 55 of 100 — class B — balanced. Engine evaluation of the starting position: +25 centipawns for White (depth 46, 400 000 000 nodes).
Explore position #231Provenance
Mined from the project's engine self-play games.
Pack 015 · SP-231
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