Tactics: That damn fork on c7
Right now, I am just adding some content, it might become an article at some point.
Knights are often used for forks, with their unique moving and jumping ability. A common situation is a knight jumping to c2 or c7, thereby threatening both the enemy rook and the king. Such "king forks" are particularly effective, because the opponent is forced by the rules of the game to alleviate the threat to the king. The opponent cannot choose to defend the other piece, and thus cannot use a zwischenzug to complicate the situation.
http://en.wikipedia.org/wiki/Chess_tactic#Fork
Here an illustrating game, Kasparov vs. the World:
We could notice that a variation on this motive is the fork between the King on d8 (or d1) and the Rook on h8.
Just two examples of that special case taken from 2 nice opening traps:
1) Alapin Sicilian
2) French Advance
Such misadventures explain why it is recommended to beginners to castle quickly!
This is probably one of the traps which you learn quickly, just after the Scholar's Mate . I remember learning it the hard way. It took me more than one game!
Later, you try to make it to your opponent all the time.
But sometimes, it's justified to authorize your opponent to make that fork: very often, the Knight will die in the corner and taking that Rook takes some time. When you want to use that idea, you need to ask yourself:
1. Can I save my Knight?
2. Am I not losing time for more important things?
Here a few examples where the sacrifice can occur:
In the Dracula-Frankenstein variation:
There are many examples in the Smith-Morra Gambit.
Here a first one from the Smith-Morra Gambit, declined with a fork on c2 and one on c7, but it's in White's favour:
An other line of the Smith-Morra gambit which isn't recommended by theory for Black . Again knight forks are very important:
King's Gambit à la Steinitz. Actually, this is called the Mason Gambit (1.e4 e5 2.f4 exf 3.Nc3 Qh4+ 4.Ke2), even though Mason didn't play it very often:
The fight against the Knight in the corner is an interesting one: is he gonna come out or not? With a knight on a8, there are only 2 possible squares to escape: c7 or b6.
Both armies try to control it with multipurpose moves. Multipurpose moves because if you only focus on the knight, you might lose the game somewhere else on the board.
Typical ideas for White are:
- Bf4 developping the Bishop and controlling c7
- Be3 attacking a7: if a6, then Nb6 and if b6, white might sacrifice the knight for 2 pawns
Typical ideas for Black:
- e5 (a move in the center, preventing Bf4 and liberating the Bf8)
- b6 followed by Bb7 and, only when necessary, Bxa8 [if the King is on the 6th rank, it might be better to recapture with the Rook].
Threatening that fork, useful or not?
But before it comes to this, it's always interesting to see whether trying to fork will be useful or not. You can see many examples of that in the Dutch defense [examples to follow], where Nd5 can be deadly.
Nd5, when possible is often more effective than Nb5 and that for obvious reasons:
- it's a move towards the center
- one standard defense is ... Na6 followed by ... c6. With the Knight on d5, the Na6 is more vulnerable to attacks like e.g. Bxa6. Paradoxically, the Nb6 might cover the Na6 :) If Black can implement ... Na6 followed by ... c6, then trying to fork on c7 was only a loss of time for white and Black will probably have an excellent position. The Na6 can rebound to c5, b4 or c7.
Even if the King is not on e8 anymore, the Rook could be captured if it has no air (pawn on a7, Knight still on b8). But be careful, it could be a bad idea.
Look at this:
