Back-rank mate in 3 on a8 (f3)
li-03Q6inaming tag (square·N)Opens in the app if installed, otherwise downloads the APK.
The tactical motive
Back rank: the king is trapped behind its own pawns — use that.
Mate in 3: a forced sequence that ends in checkmate.
Difficulty 1128 ShuffleRating — club-player level.
White to move — find the best continuation
How to recognize this tactic
A back-rank mate strikes when the king is boxed in by its own pawns and the back rank is under-defended. Check whether a rook or queen can reach the first rank with check and whether the only defender can be deflected or overloaded.
In a mate in three every move must be forcing; the defender should never get a free tempo. Find the check or threat that herds the king, calculate the single defence to each, and confirm the net closes on the third move.
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 g1, queen f3, rook a1, bishop g3, pawn f2 g2 h2 e5.
Black: king g8, queen b6, rook a2 a8, pawn c5 c7 f7 g7 h7.
8 white and 9 black pieces are on the board; the puzzle position arises after move 28.
The position in numbers
Black are ahead by 3 points of material (21 against 24; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on g1, the black king on g8.
It is White to move on move 28, with 31 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 4 pawns, Black 5. Files fully open (no pawns of either colour): a, b, d — natural highways for the rooks and queen. Half-open for White: c.
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
28. Qxa8+ Rxa8 29. Rxa8+ Qb8 30. Rxb8#
Why it works
- Great move! queen to a8 keeps the pressure (#2).
- Well found: rook to a8 (#1).
- Strong! rook to b8 is the sharp choice (#).
- The line ends in a forced mate in 3.
- If instead Rxa8, then Rxa8+ and you stay on top.
Move by move
- 28. Qxa8+ — queen to a8 (capture) with check
- Rxa8 — rook to a8 (capture)
- 29. Rxa8+ — rook to a8 (capture) with check
- Qb8 — queen to b8
- 30. Rxb8# — rook to b8 (capture) and it is checkmate
Types in this puzzle
Back-rank mate
The king is locked behind its own pawns — a heavy piece strikes the last rank.
The back-rank mate strikes a king locked behind its own unmoved pawns when a rook or queen crashes onto the last rank. The signs: no escape hole in front of the king, and the back rank guarded by a single piece or by nobody at all. Often that lone guard is deflected or traded off first, and only then comes the invasion. In your own games, make luft in time — one pawn move prevents a sudden catastrophe.
Only move
Everything else loses — find the only move that holds.
An only move is a position where everything loses except one single continuation. You cannot play "by hand" here: run through fundamentally different defenses — run away, block, trade, counterattack — and discard the ones that fail. The hallmark of these puzzles is that the obvious moves lose quickly while the solution often looks strange. First understand exactly what the threat is — then the one saving move reveals itself.
Mate in 3
A forced checkmate in three moves.
Mate in three is a forced staircase: each of your moves narrows the opponent's choices, and the third one ends the game. Look for the start among checks and sacrifices — quiet first moves are rare in mating problems, but deliciously sneaky. Keep the tree in your head: every defense gets its own branch. Do not stop calculating after move two — see the final mating picture with your own eyes.
Provenance
Derived from the Lichess puzzle database (CC0).
Verified by Stockfish at depth 20+.
Solution forcedness confirmed (verified).
Pack 007
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