The solution was en passant, a move that allows a pawn that has moved two squares to be captured as though it had only moved one. The diagram above illustrates how en passant works. The following conditions must all be present for an en passant capture to be legal: The capturing pawn must be on its fifth rank.
En passant is the most commonly misunderstood rule of chess! At some point every chess player is shocked the first time their opponent uses the en passant capture rule. For you to capture en passant your opponent’s pawn MUST move two squares forward, landing next to your pawn.
En passant (French: [ɑ̃ paˈsɑ̃], lit. in passing) is a move in chess. It is a special pawn capture that can only occur immediately after a pawn makes a double-step move from its starting square, and it could have been captured by an enemy pawn had it advanced only one square.
However, they are also the only chess piece that captures in a method different from how they move. To capture, the Pawn moves diagonally one space (see the diagram). The Pawn can never move backwards. The Pawn also has a special move called “En Passant”, which you can read about in special moves section below.