The En passant... why only pawns?

So I had an interesting position in a recent game and it brought up a question that I have never thought about before. Why is en passant only allowed to be between pawns?

Basically I had a bishop on b5, he played a5, and I wasnt sure why I could not play Bxa6, as anywhere else on the board, the pawn could only move 1 square- which is why the move exists in the 1st place. But why is it only for a pawn to take en passant? Shouldnt it be allowed by any piece that the pawn tries to escape from by making the double move?

This may sound like a silly question, but think about it, why shouldn't it be possible? Im a pretty decent player, but this is the 1st time the issue has crossed my mind, so I was hoping someone had a clue.

The only reason en passant exists is to stop pawns from advancing 2 squares - beyond an opponent's advanced pawn - thus shoring up the lines. Pieces move differently than pawns, so it's not really an issue with them; the main idea is so that the captured pawn can't "escape". I imagine that without en passant, chess games would be a lot duller and feature a lot more closed positions.

It's an interesting idea you have, but I don't think there's any need for pieces capturing en passant. Advancing a pawn beyond a piece is not a permanent case of "passant" as doing so with another pawn. Once the pawn advances beyond the reach of an opponent pawn, it's done so permanently; a piece can always move back where it came from.

I hope that makes sense :P

Yep, that does. So basically it is because pawns cant move backwards, but I still wish pawns couldnt escape a capture by moving 2 squares, regardless of the piece. I understand the purpose of the initial boost in squares, but to use it as a tool to escape an attack is unfair in my opinion.

But imagine we're playing, and I have a strong attack. I play e5 (I'm white) and you think "man, I'm going to get ripped open. I better close all the lines by playing f5!"

So you play f5; the lines have been closed, making my attack less dangerous, but there is no en passant rule. You get off the hook, and the game is going to be a closed, positional struggle from here on out. However, if I can play exf6 en passant, it's not so easy for you to get out of jail, and the game will be more open and more exciting!

That's my view anyway; apparently both the en passant rule and that which says that a pawn can move 2 squares on its first move were introduced in the 15th century. I guess someone said "ok, we can allow the new 2-square push, but if you do it purely to get away from my advanced pawns then I'm allowed do THIS!" *captures en passant*

Evidently the number of people who thought it was a good idea outweighed the number of people who thought the guy was high as a kite.

I completely agree with the en passant. I think its always been a great move, and I like your explaination as well. I just think pawns shouldnt be able to "get out of jail so easily" as you put it, whether by an attacking pawn or a piece.That is my concern/confusion. I understand the necessity of the move for pawns, as they cannot move backwards, but I guess I'm still a little confused as to why a pawn gets such a luxury against an attacking piece. Maybe because of the pieces mobility on the board? I just think it would add an entirely new amount of pressure if the pawns could be taken en passant with a piece as well if its attacker can block a 6th rank pawn from advancing to 5th, shouldnt one blocking the 6th rank stop one from the 7th jumping to the 5th?

Like I said, in the thousands of games I have played, the possibility of an en passant with a piece (even though its not a legal move) has only come about a handful of times, so its not really a big deal, and I can just write it off as a "because thats just the rule"- like the way a knight moves, but I was just wondering the logic behind it. But again thank you for your thoughts.

You certainly raise a good question.  I for one wouldn't change a single thing about chess as I think it is a perfect balanced game as it is, but I agree I have wondered in the past, like I am sure many before us have, why they made it just pawns.  We will never really know I guess.

All the other pieces move differently?  Maybe that is one of the reasons. :D 

Seems like a slightly random comment.  The OP is referring to when any piece could have captured the pawn moving 2 if it had only moved 1 square.  Regardless of how the potentially capturing piece moves it should have the same opportunity as the pawn to take the enemy pawn.

I think it is part of the balance of the game. The pawns are granted special powers to make up for their lack of normal ones. By confining this ability to pawns they have a unique defense against - and an attacking advantage over - the big bad pieces.

Interesting on comparing pawns and the pikeman.

good comments, and a nice history lesson too. I guess I'm just going to go with the "because thats the rule" philosophy :)

On another note regarding pawns, has anyone seen the 3rd millennium chess sets? www.3mchess.com

They had them at the last tournament I was in. I thought it was pretty neat. There are 2 sets of pawns (thought they cannot move backwards still), and knights can split and reattach. Seems interesting, waiting for the online version.

A few hundred years ago pawns were not able to move 2 squares on their first move.  In order to speed things up they were granted the ability to move 2 squares on their first move.  It was soon realised that it created an unexpected problem that the pawns could advance without risking capture by another pawn when the challenging pawn was on its' fifth rank.  En passant was then introduced as basically a hack to overcome the obstacle presented by granting pawns the ability to sprint and thereby speed up the game a bit.

Also Bishops used to only be able to move 2 squares at a time and could jump over pieces like the knight.  Queens could only move 1 square in any direction and either the King or the Queen, I don't recall offhand, was not allowed to move backwards diagonally.  Chess evolved for quite awhile but has been a little stagnant of late.  Perhaps it is time for a little overhaul to throw the computers a bit of a curve.

Plenty, alot of the  comments here are random and half thought through,  it was a general statement.  :)  I understood what he was trying to say.