Forks in Chess
A fork in chess is a manoeuvre whereby a piece attacks two opponent pieces in one move. Any piece aside from the king can perform a fork on the opponent and many factors determine how successful the fork is in gaining an advantage over the opponent.
Forks can be broadly separated into two categories - absolute forks and relative forks.
Absolute forks
An absolute fork is one which involves the opponent’s king. This means that the player puts their opponent in check and, in the same move, threatens to take another piece. To understand this better, let’s consider this simple example:
Here the black bishop on c3 is checking the white king, while also threatening to take the white rook on a1. The name absolute fork here comes from the fact that white must now, in order to make a legal move, remove themselves from check, either by moving the king, taking the bishop, or moving another piece in between the bishop and the king. This means that, if white cannot take the bishop, black can take the white rook with the following move, making it an effective fork. If we change the scenario a little and add a white knight to the mix, we can see how this fork might not be so effective:
Now, the fork is not so effective, since white can simply take the bishop with the knight on b1. Therein lies the first and potentially most important factor of executing an effective fork - protecting the piece that is doing the forkning. There might be some occasions where this would still be effective, if, for example the black queen was lurking somewhere nearby to jump in and take the white knight once it had captured the bishop.
Let’s take a look at another common absolute fork scenario, which occurs frequently in gameplay. This is involving a knight:
This scenario is extremely beneficial for black, since white is now in check and must do something to get out of check. If the black knight is not under threat of being captured, then black will take the white queen on the next turn. Knights are often used as a piece to fork the opponent’s queen, since the queen is not in a position to take the knight, whereas bishops and rooks are both in the line of attack of the queen, so must be protected in order to successfully fork the queen. In the above scenario, the white king will almost certainly find itself in a position to take the knight once it has captured the white queen, although this is a trade that black will be happy about, since the knight is considerably less valuable than the queen - check out our piece on piece values for more info.
Knights also have the obvious advantage of attacking a squares directly, and doing so in spite of any intervening pieces. This results in forks by knights usually working well, since the option to put a piece ‘in-between’ in not available to the defending player. They must either move the king or take the knight.
Relative forks
The second type of fork to discuss is the relative fork. This doesn’t involve checking the opponent, and so presents your opponent with a choice. Let’s take a look at an example:
Here the black bishop is forking the white rooks. White, in this scenario, now has a choice. The choice is not difficult, since the piece at stake is the same, so white must decide which rook to lose. Of course, if one is being protected and the other isn’t, it would be beneficial to move the unprotected piece, in order to take the bishop after it has taken the other rook. However, if neither or both are protected, it makes sense just to choose to lose the rook with the worse position, meaning the one that is less likely to help with attack/defence in the coming moves.
Escaping relative forks
The principle behind relative forks is quite simple, but it’s worth looking at some techniques to escape from them, if your opponent manages to fork two of your pieces. Here are a few key manoeuvre to consider:
- taking the piece performing the fork
- pinning the piece performing the fork
- checking with one forked piece and saving the other on the next move
- threatening a high value piece with one of the forked pieces and saving the other on the next move
- moving one forked piece to protect the other
Taking the piece performing the fork
As you would expect, the best and simplest way to save a fork situation is to simply take your opponent’s piece performing the fork. This is obvious in most scenarios, but should be a rare occurence, since your opponent will not likely leave the piece open to being taken. Let’s see an example like before, trivial as it may seem.
Clearly in this example, the white knight on b1 can take the bishop and prevent either of the forked rooks from being taken.
Pinning the piece performing the fork
Pins are covered in further detail in our piece dedicated to pins. In essence, you prevent the piece from moving from in front of its king, since doing so would result in check. Let’s see this in action.
Here, white finds its rooks on d1 and f1, and black has advanced a pawn all the way up to e2. This pawn is now forking the two rooks and is in a position to take either. White, however, can escape from this fork by moving either rook to e1. This rook is now pinning the pawn in its position and preventing it from taking the other rook. Black, on the next move is likely to move the king and avoid the pin, but at this point, assuming it can do so, the other rook can simply move away.
Checking with one forked piece and saving the other on the next move
This can also be an effective way of escaping from a fork. One of the forked pieces attacks the king and forces the opponent to escape from check. On the following turn, the other forked piece can save itself from attack. Here’s an example:
Once more we have rooks on d1 and f1, this time being forked by the black knight. A pin is not possible in this scenario, but white can advance either of the rooks to the 7th rank and check the black king. Then, once black has escaped from check, the other rook can move clear of the knight’s path.
Threatening a high value piece with one of the forked pieces and saving the other on the next move
The distinction between this escape and the previous one is similar to the distinction between relative and absolute forks themselves. One of the forked pieces is used to attack a high value piece of the opponent’s, forcing the opponent to move that high value piece to safety before the other forked piece can move. Let’s see an example of that in action:
Similar to the previous example, the black knight is forking the two white rooks, only this time black’s queen is in play and can be directly attacked by one of the white rooks. There are a couple of pre-requisites for this move though.
- The piece threatening the high value piece must be safe. Depending on the piece, it must be protected from the high-value piece and any other of the opponent’s pieces.
- Taking the remaining forked piece will not result in check.
If we add in a couple of other pieces to the previous example, we can see how this escaping technique might not be applicable.
Here we have pawns in front of the two white rooks to prevent them from moving up next to the black queen and the bishop on a3 is ready to capture the rook if it moves to c1 to threaten the queen.
Let’s also take a look with the king in action:
Here the rook on d1 is actually safe to move to c1. The other rook is protecting it from capture by the queen and it can therefore threaten the queen to escape the fork. However, black need not worry about that in this scenario, since taking the rook on f1 would result in check, so white would be unable to take the queen on that move. Instead, white would be forced to evade check first. At that point, black could move the queen to safety and would have successfully perform the fork.
Moving one forked piece to protect the other
This technique only works for scenarios where the piece threatening the fork is of equal or higher value than the forked pieces, or to be more specific, than the piece that is not moved. Let’s see an example to understand better how this works.
In this scenario the black queen has forked the two white rooks. However, a simple escape for white is to move one of the rooks to cover the other one. Moving either rook to a4 or d1 would mean that they are both protected and the black queen would be unlikely to take them at that point in time. The pre-requisite is that the rook - the piece under attack - is of lower value than the queen - the piece performing the fork. Let’s change that and look at a slightly different scenario.
Replacing the queen from the previous example with a bishop, the fork now becomes quite effective. It’s true that white can protect its rooks, but since the bishop has lower value than the rook, black would likely take whichever rook was left in place, and allow the bishop to be taken on the following move. Again, if you’re not sure why that’s the case, then our article about piece values is the right place to go.
That pretty much wraps up the introduction to forks. There are many applications of forks in chess games and hopefully you have learnt how to execute and escape from them.
If you have any comments, feedback or questions about anything in this post, leave them below.