Explanation

This pattern is also known as the "guéridon mate". Either name is derived from the "Y"-pattern of the pieces involved in the checkmate. A swallow's tail does look like a Y, and a gueridon is a small table that looks like a Y.

Examples

White can win with the Swallow's tail mate Qe6#. The queen not only delivers checkmate, but also guards most of the king’s escape squares: e8, d7, f7, d6, and f6. The remaining two escape squares are blocked: d8 by the black queen, and f8 by the black bishop.

A swallow's tail mate is also sometimes possible with a rook when other pieces guard or block the additional escape squares:

Black can deliver swallow’s tail mate with Rhb2#. Here the additional escape squares are a3 and c3 - c3 is blocked by a pawn, and a3 guarded by the rook on a2.

Pattern matching

This pattern can happen if the opponent's king is in front of its own pieces, for example in endgames, or if the king was forced out of its initial or castling position by an attack.

Related patterns

Related patterns are the dovetail (the queen is diagonally adjacent to the king) and epaulette mates (the queen is not adjacent to the king).