Reason for the rule of pawns attacking diagonally

I was teaching a person chess and they asked why pawns don't attack the way they move, as all other pieces do. I agreed that the rule seems unintuitive enough (from the perspective of a new player and game development in general) that there probably was a good reason. I said that my best intuition is that it would give the opening player some undue advantage but I couldn't think through exactly how at the time. From my limited research, I found that pawns have attacked like that since before chess even existed (like in precursor games like chaturanga). Because of that, I imagine there's no historical record of when and why pawn attacking rules were developed as they are. However, does anyone know if it's the case that if pawns attacked forward one square instead of diagonally, though we could also consider in addition to, the game would be unfun or unplayable (e.g., guaranteed win for white or heavy advantage; quick, forced draws, etc.)?

Hi LetThaWookieeWin,

Excellent question. The game would fundamentally change because we would no longer have the pawn structures we are used to, which are shaped and defined by the fact that when two pawns meet head on they lock themselves into position until one of them is captured by an adjacent pawn or piece. Having the ability to capture forward with a pawn would greatly increase the potential to open board, thereby increasing the value of the bishops relative to the knights (which are currently useful for their ability to hop over locked pawn structures). I don't know if it would be unplayable or unfair, but I do think it would be a fun variant to try.

Thanks for your post!

Reason for the rule of pawns attacking diagonally

When warriors move, they step forward.

However, when they unleash their sword, they attack diagonally (because their hands have to reach out to where the sword is, before wielding the sword in a diagonal manner). Once the attacks are done, the warriors occupy that square.

     It would seem to give white an advantage. After 1.e4, the move 1....e5 would just drop a pawn. And it would be impossible for a piece to block a pawn's advance toward the eighth rank. And would the pawn also be able to capture diagonally?

It's important to remember that the diagonal-capturing pawn is much older than the modern  bishop.  So it wasn't designed that way for the purpose of blocking up bishops, it's just an interesting side effect.  Also, shogi and xiangqi both have pawns that move and capture one step orthogonally forward.

Imagine that the pawns have shields and swords, the idea is that when they are facing each other they block each other by the shields and attack diagonally because with the swords they attack defenseless points.

...its all arbitrary. just like castling & enpiss ant.

It would do away with closed positions since pawns can't defend each other any longer. Pawns are fundamentally different, just like civilians are from soldiers. And that's for a reason; they provide the democratic structure around which the statesmen maneuver. They're the skeleton for the organic infrastructure to constitute the organism of chess. They're the *insert another metaphor 

I think it's because pawn was supposed to teach you about infantry formation. Shogi pawns however, attack one square forward. So they rely on silver or gold generals for protection

If chess pawns was also attack one square forward, I think we won't get bishop, or even alfil. We might get mann or something like that

Because one pawn cannot protect another pawn in that case

Took me a hella long time to realize what you meant by "enpis ant" lol

The rule of pawns attacking diagonally in chess serves multiple purposes. It reflects the historical origins of pawns as foot soldiers in warfare and adds a strategic dimension to the game. Diagonal capturing enhances the complexity of chess, allowing for defensive chains and promoting positional play. It helps balance the power dynamics between pawns and other pieces, while also incentivizing pawn advancement and promotion. Overall, the rule adds depth, historical context, and strategic opportunities to the game of chess.