Alekhine's gun

Alekhine's gun is a formation of the heavy pieces, meaning the queen and rooks. All three stand on one file, a vertical line of the board, with both rooks in front and the queen behind them. The leading rook forms the point, the second rook reinforces it, and the queen supports both from the rear.

The formation is especially useful on an open file, one containing no pawns, or a half-open file, one containing no friendly pawn. It can pile attackers onto a piece, pawn, or entry square. It may also be assembled on a closed file when there is a concrete way to open that file before the opponent reorganizes.

The shape alone is not enough

• The file must lead to a real target or an invasion route.
• The setup takes time; slow maneuvers may surrender the initiative, the ability to keep the opponent answering threats.
• The front rook needs a useful advance, exchange, or capture rather than becoming blocked.
• A concrete combination, a forcing sequence built around one tactical idea, may matter more than completing the formation.

The name is associated with Alexander Alekhine's game against Aron Nimzowitsch at San Remo in 1930, where Alekhine completed the arrangement by placing his queen behind both rooks. Earlier examples of the same geometry exist, however, and the exact printed origin of the name remains uncertain. It is therefore more accurate to say that the game made the formation famous than that it invented it.