Chess960 tactic on a4 (a1)
c9-09319naming 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 b1, queen e7, rook a1, bishop f1, knight f8, pawn b2 g2 d3 f3 a5 g5.
Black: king d4, rook a8 d8, pawn e3 g3 a6 b7 g7.
11 white and 8 black pieces are on the board; the puzzle position arises after move 35.
The position in numbers
White are ahead by 11 points of material (26 against 15; 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 d4.
It is White to move on move 35, with 31 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): c, h — natural highways for the rooks and queen. Half-open for White: e.
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
35. Ra4+ Kd5 36. Qe6+ Kc5 37. Rc4+ Kb5 38. Qb6#
Why it works
- Great move! rook to a4 keeps the pressure (#2).
- Spot on — queen to e6 (#2).
- Precise: rook 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 Kd5, then Qe6+ and you stay on top.
Move by move
- 35. Ra4+ — rook to a4 with check
- Kd5 — king to d5
- 36. Qe6+ — queen to e6 with check
- Kc5 — king to c5
- 37. Rc4+ — rook to c4 with check
- Kb5 — king to b5
- 38. Qb6# — queen to b6 and it is checkmate
Types in this puzzle
Ladder mate
Two heavy pieces climb line by line, cutting off every retreat.
The ladder mate uses two heavy pieces climbing rung by rung: one cuts the king off along a line, the other checks on the next line, driving him toward the edge. It is the classic two-rook technique — check, the king retreats one rank, the other rook checks, until mate on the last rank. The only danger is the king creeping close enough to attack one of your rooks. If it does, simply slide that rook to the far side of the same line.
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.
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.
About this position
These pieces come from starting position #890.
SP-890 · BastionScout — The king starts one file off-centre, on c or f, and a knight begins in a corner.
The king starts on c1, the rooks on a1 and d1, the queen on b1.
The king already stands on c1, so castling long moves only the rook, from a1 to d1.
The bishops stand on e1 and f1; their long diagonals reach a5 and a6 once the d- and e-pawns step aside.
One second-rank pawn starts with no defender at all: h2.
The setup belongs to the BastionScout family; read right to left it becomes position 69.
The engine's main line opens with e3.
Morozov Balance Index: 83 of 100 — class A — most balanced. Engine evaluation of the starting position: +16 centipawns for White (depth 43, 400 000 000 nodes).
Explore position #890Provenance
Mined from the project's engine self-play games.
Pack 015 · SP-890
Similar puzzles
In your browser or in the Android app. Nothing to install · Free, no ads