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The swallow’s tail mate is a close cousin of the dovetail, but the geometry is turned by 45 degrees. The queen stands directly in front of the king, on the same file or rank, protected by another piece. It covers every square around the king except two: the diagonal squares behind it. When the defender’s own pieces sit on exactly those two squares, the king is trapped, and the shape around it looks like a forked tail.
It happens most often when a king has been forced out of its castled position and is wandering in the middle of the board.
The mating position
A clear example: Black’s king is on e7, with black rooks on d8 and f8. White’s queen lands on e6, directly in front of the king, protected by a white pawn on d5.
Now check each square around the king:
- e6: the queen, defended by the d5 pawn, so it cannot be captured.
- d6 and f6: on the sixth rank, covered by the queen.
- d7 and f7: diagonally next to the queen, covered.
- e8: on the e-file behind the king, still covered by the queen’s line.
- d8 and f8: the only squares the queen does not reach, blocked by Black’s own rooks.
That is mate. The pattern can be rotated in any direction: the queen beside the king on a rank works the same way, as long as the two diagonal squares on the far side are filled by the defender’s pieces.
Spotting it before it happens
The swallow’s tail rarely appears against a king tucked safely behind pawns. Watch for these situations:
- The king has been chased up the board, often after a sacrifice on f7 or e6.
- Your queen can land directly next to the king, and you have a pawn, knight or bishop to support it.
- The defender has pieces crowded behind the king, typically rooks or minor pieces that were never developed or that retreated.
The key move is often a quiet preparation: a pawn push that will support the queen’s landing square, or a knight hop that controls it. After that, the queen check is the finishing blow.
Common errors
The attacker’s typical slip is confusing this with the dovetail. If the queen stands diagonally next to the king, the uncovered squares are different, and you need different blockers. Always count around the king square by square. Also make sure the queen’s protector cannot be captured or pinned first.
The defender’s mistake is usually a crowded back rank behind a king that has already left home. Rooks or bishops sitting on both diagonal retreat squares turn into prison walls. If your king is in the centre and the opponent’s queen is getting close, try to keep at least one diagonal escape square free.
How to practise it
- Learn the pair. Dovetail: queen touches the king diagonally, two straight squares blocked. Swallow’s tail: queen touches it straight on, two diagonal squares blocked. Knowing both stops guesswork.
- Look for the protector first. A queen next to the king is only mate if it is defended, so find the supporting piece before calculating anything else.
- Use hints wisely. If a puzzle feels stuck, ask which square next to the king your queen could reach with support. That question usually reveals the answer.
A few rounds of these puzzles and you will instantly see when a centralised king is one queen move away from defeat.
