En passant: why a pawn disappears from the adjacent square
Sometimes a pawn moves diagonally to an empty square and a neighbouring pawn disappears. This is a legal en passant capture. Look beyond the piece arrangement: the opponent's last move matters. A similar position reached by a different move does not grant the right.
In this article
Check the last move, not just the neighbour
An ordinary pawn capture ends on the target's occupied square. Here the target has just advanced two squares from its starting rank and stopped beside your pawn. You capture it as though it had moved only one square. For White this usually goes from the fifth rank to the sixth; for Black, from the fourth to the third. A neighbouring pawn arriving by a single step cannot be captured this way.
Follow the example from the start
White plays e2–e4 and Black a7–a6; White then advances to e5. The reply d7–d5 places Black's pawn beside it. Now e5–d6 removes the pawn on d5, although d6 was empty. The a7–a6 move only prepares the teaching position: this line demonstrates a rule, not an opening repertoire.
Do not postpone it; check king safety
The opportunity exists only on the immediate reply to the double step. You may decline, since chess captures are usually optional. But after a different move of your own, you cannot return to this capture. Another trap is opening a line to your own king. With White's king on e1, pawn on e5 and Black's rook on e8, leaving the e-file exposes the king. The special pawn rule does not permit leaving your king in check.
Exercise: explain the missing pawn
Pause before the last step. Name the starting square, destination and removed pawn's square, then verify on the board. Repeat the first four steps in practice but make a different legal move instead of capturing: after Black's reply, e5–d6 should no longer be available. Ask three questions: was there a double step, am I replying immediately, and will my king remain safe?
Your move now.
Practise the idea on the board. You can make mistakes, try again and start over.
Open exerciseRules and sources
Use these links to check the rules and explore the topic further.