What Is En Passant
This is another of the special and complicated moves in chess, and like castling, beginners often make mistakes when trying to capture en passant.
It helps to understand how this rule works if you’ve heard of a little history. Today, a pawn has the option of moving straight ahead two squares on it’s first move, and at all other times can only go one square on each move. But centuries ago this wasn’t allowed — pawns could only move one square at a time. This meant that sometimes a pawn could fly past an enemy pawn with no chance of capture at all. This didn’t seem right, so the en passant rule was invented. The rule gave the other side the right to capture such a pawn that flies past it by going two squares on it’s first move, as if it only moved one square. That allows one side to cancel out the special move by the other side if they want to. But it has to be done right away. If it’s not done immediately after the other side moves their pawn two squares, it’s not allowed to capture that pawn by the en passant rule again.
In other words, the rule goes like this, if a pawn moves two squares on it’s first move, a pawn of the other color on the square to it’s side can immediately capture it as pawns normally capture. Remember pawns always capture on the diagonal. So the capturing pawn moves into the empty square the other pawn just passed over, and removes the enemy pawn from the square it’s on.
This is an exception to the rule that chess pieces always capture by replacing the opposing piece on the square it occupies. It’s the only exception to the rule that captures happen when you “land on” an enemy piece.
Maybe some pictures will help make this rule clearer.
The last and most complicated special rules about pawns is called “en passant,” which is French for “in passing.” Lots of beginners make mistakes about this rule for awhile–don’t worry about it, it just takes some getting used to. This special rules applies anytime right after one side chooses to move a pawn forward two squares on it’s first move. If the other side could have captured the pawn if it had only moved one square, that player has the option to capture the pawn by “pretending” it did move only one square. This is the only move in chess that lets a player capture an enemy piece without occupying the square that piece was on. Let’s look at some diagrams to explain this again. In the first picture, White has a pawn on the fifth rank, and on an adjacent file Black has a pawn that hasn’t yet moved. The way it works out, the White pawn must be on the fifth rank for en passant to be possible.
Then Black chooses to move his pawns two squares at once on it’s first move. Now it’s n the square next to to the White pawn on the side. It the Black pawn had only moved one square on it’s first move, the White pawn could have captured it, but the Black pawn raced past that square, thinking it would be safe. But not so. White remembers the en passant rule. As long as White does it right away, he can pretend that the Black pawn only moved one square, and capture it anyway, ending up with the final position showed in the picture on the right.
In order to capture en passant, it has to be done immediately after the enemy pawn moved two squares. If White chooses to do anything else, he forever gives up the chance to capture that pawn en passant. White doesn’t have to capture that pawn en passant if he doesn’t want to. Of course, if the situation allows it, either side can capture other pawns en passant on other moves.
This is the only time in chess that a capture can be made without occupying the square the enemy piece was on. It’s a very special move, and it’s very important to know how it works, even if you don’t use it all the time.