Attack on the uncastled king: pawn to e4 (f3·33)
c9-19945naming 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.
Uncastled king: the enemy king is stuck in the centre — punish it before it castles.
Winning tactic: there is a move that gains a decisive advantage — find it.
Difficulty 920 ShuffleRating — for beginners taking their first steps in Chess960 tactics.
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.
An uncastled king in the centre is a standing target. Look for ways to open the central files and diagonals against it with checks and threats before it can shelter — every tempo the king spends in the middle is a chance for a combination.
This position hides a concrete tactic that wins material or mates. Start with the most forcing candidate moves — checks, captures and threats — and calculate each to a clear end before choosing; the winning line is usually the one the opponent cannot meet.
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 e2, queen a2, rook d1 f1, bishop g1 h1, knight d3, pawn h2 b3 f3 a5.
Black: king e8, queen c7, rook d8 f8, bishop c3, knight d5, pawn e4 f4 b5 c6 g6 a7 h7.
11 white and 13 black pieces are on the board; the puzzle position arises after move 20.
The position in numbers
Material is level — 32 points of pieces on each side (pawn = 1, knight and bishop = 3, rook = 5, queen = 9).
The white king stands on e2, the black king on e8.
It is White to move on move 20, with 35 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 4 pawns, Black 7. Files fully open (no pawns of either colour): d — natural highways for the rooks and queen. Half-open for White: c, e, g.
White hold the bishop pair, an edge in open lines. The White king has 1 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
20. fxe4 b4 21. exd5
Why it works
- Great move! pawn to e4 keeps the pressure (+1.8).
- Spot on — pawn to d5 (+2.7).
- You win a piece — the knight.
- If instead b4, then exd5 and you win the knight.
Move by move
- 20. fxe4 — pawn to e4 (capture)
- b4 — pawn to b4
- 21. exd5 — pawn to d5 (capture)
Types in this puzzle
Winning blow
Find the strike that wins material by force.
A winning blow is a forced material gain that does not fit a single textbook motif. The general tactical recipe applies: spot loose pieces, an awkwardly placed king, overloaded lines. Go through the forcing moves in order of violence — checks, captures, threats — because most combinations start with one of them. Do not judge by feel: calculate the concrete line until the outcome is beyond doubt.
Uncastled king
The king lingered in the middle — punish the delay.
Punishing the uncastled king: your opponent delayed castling, and now his king is stuck on its starting square under fire. In Chess960 this is deadlier than in classical chess — the king may start in the center or near the edge, and the familiar defensive setups simply do not apply. The signs: the victim still holds castling rights, and the files toward his king are half-open. Open lines before the king manages to hide.
About this position
These pieces come from starting position #415.
SP-415 · ThroneGuard — A central king (d or e) and two knights tucked onto inner files: the family that holds the standard array, SP-518.
The king starts on e1, the rooks on a1 and f1, the queen on b1.
The kingside rook already stands on f1, so castling short moves only the king, from e1 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 d2 is defended by the king alone — the same soft spot f2 is in the classical setup.
The setup belongs to the ThroneGuard family; read right to left it becomes position 736.
The engine's main line opens with e4, putting a pawn straight into the centre.
Morozov Balance Index: 47 of 100 — class C — noticeable edge. Engine evaluation of the starting position: +27 centipawns for White (depth 45, 400 000 000 nodes).
Explore position #415Provenance
Mined from the project's engine self-play games.
Pack 005 · SP-415
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