Special Pawn rule - Enpassant rule

Comes once in a while concept, yet can't be easily overlooked. Let's try to understand Enpassant rule & how we can utilize it to our benefit. 

Enpassant rule is not compulsory to opt. You can choose not to use this concept in case it brings misfortunes to your position. This can come as a hidden technique if in case your opponent is unaware of it. Enpassant rule is applied only to pawns and not always we can use this. Certain conditions must be met to use Enpassant rule by the pawn. 

Let us see what Enpassant rule is with an example and what all are the conditions to be met to use this concept.

"En passant" is a French word that means "in passing". This is exactly how the capturing works as well.

Enpassant Definition: En passant rule is a special type of rule in which a pawn is allowed to capture opponent's pawn on an adjacent squares under certain special circumstances. 

Till now we have known pawn to capture on an immediate diagonal only, like shown in the position. 

Here, the pawn on g4 can either capture black's f5 or h5 pawn. This is how normally pawn capture works.

Here, the white pawn has successfully captured the black pawn in h5, therefore the notation is 1. gxh5. 

After the capture, the white pawn has replaced the black pawn's original position.

But in Enpassant rule, the pawn can capture the opponent's adjacent pawn, which is not present in its immediate diagonal square. 

Let's look at an example:

The position is like this, where it's the black turn to play. Note that white pawn is in the 5th rank. Now what happens if black plays 1... e5, pushing its pawn two squares forward which lands it exactly adjacent to the white pawn in the 5th rank?

For e5 pawn push, here e5 square is not in diagonal to f5, normally we can't capture the pawn but white can use Enpassant rule to capture the adjacent pawn in this move, however here white pawn doesn't replace the black pawn's original position instead it behaves as if it has captured the pawn on the e6 square.

Therefore, the notation is 2. fxe6 e.p. Honestly, in e6 we didn't have anything to capture, it is the e5 pawn we have captured using the Enpassant rule.

There are certain rules we must mind while executing Enpassant rule to make sure it's legal.

Like any other concept, this can be applied to white or black, fulfilling certain conditions. As mentioned earlier, not always this concept can be utilized. Therefore, we must keep in mind the rules for using the Enpassant rule.

The Enpassant Rule says:

1. The capturing pawn (white pawn in the above example) must have moved exactly three ranks from its housing position to perform this move. e.g. - For white its 5th rank and for black, its 4th rank, respectively.
2. The captured pawn (black pawn in the above example) must have moved two squares in the same move from its housing position, landing right next to the capturing pawn.
3. The en passant capture must be performed on the turn immediately after the pawn is moved next to the capturing pawn. If the player does not capture en passant on that turn, then they no longer can do it in later moves. Think of it as a onetime offer only.

Lets see the situations where we cannot perform the Enpassant rule:

1. One Square instead of two: We cannot perform Enpassant if opponent pawn moves from its housing position to just one square and in the next move it moves one more square, coming next to our pawn in the same rank. We can't do Enpassant because the pawn didn't move two squares in a single move. 

The sequence of this is shown in the position below. (The annotation B/P - Black to Play)

1... e6 (one square ahead)

The initial position 1 (B/P)

   

Let us say white plays one temporary move (for demonstration purpose we have played 2. Kc2)

2. Kc2 (a tempo move)

2... e5 (one more square ahead)

In the above sequences, as the rule says, the black pawn in e7, didn't move to e5 in one move, instead it used two moves to make this change. Hence, white cannot perform Enpassant here.                          

2. One time offer: If Enpassant condition/rule is fulfilled, but you still chose to not use the Enpassant concept for this move, then you cannot use it in the future. It is a onetime offer only. 

The sequence of this is shown in the position below.

The initial position 2 (B/P)

1... e5 (a)

(a) For 1... e5, the white now has all the conditions needed to perform Enpassant rule, but here the white chooses to not use this rule and play some other move, as shown below.

2. Kc2 ( a tempo move)

2... Kc7 ( a tempo move)

It's white to play now, can white use Enpassant rule to capture the e5 pawn from its f5 pawn? No, white has lost its chance to use Enpassant on e5 pawn through its f5 pawn as in previous move it chose to play Kc2 instead of using Enpassant.

3. Enpassant Rank: For White. its pawn can capture black pawn using Enpassant if and only if it's in the 5th rank assuming all other conditions for Enpassant is met, in any other rank it cannot use the Enpassant rule. Similarly for black, pawn should be in 4th rank to use the Enpassant rule & capture the white's adjacent pawn. 

Let us see the relevant positions for the same.

For White:

The initial position 3 (B/P)

1... b5?

2. cxb6 e.p.

As soon as all conditions for Enpassant were met, the white pawn on c5 (5th rank) immediately captured the black pawn on b5 using Enpassant.

For Black:

The initial position 4 (W/P)

1. g4

    

1... hxg3 e.p.

As soon as all the conditions for En passant were met, the black pawn on h4 (4th rank) immediately captured the white pawn on g4 using Enpassant.

Can we skip this rule?

Of-course, we can skip it if we feel that the Enpassant rule will not improve our position or it will create disadvantage position for us. But once we decide to skip it in that turn, we cannot try to use it in the future turns for the same pawn. If a fresh new pawn plays two squares ahead, adjacent to your pawn, then you can choose again to either use the Enpassant concept or not, given all conditions are met.

Not always Enpassant is a good move, you must check your position before deciding to whether you will go with Enpassant or just let it slide.

Notation:

As we have seen above, the notation is quite similar to how pawn capture works, except the square it moves to is different from the square the captured pawn rests in Enpassant.

If we want to specify Enpassant, then we can add "e.p." at the end of the move to represent Enpassant. Example: From the above position, it is 2.fxe6 e.p.

En passant is a great tool to catch your opponent off-guard & to prevent you from losing materials or match due to it.

Happy Learning!