Difference between revisions 25976 and 25982 on enwiki

=== Sample Game ===

 +---+---+---+---+---+---+---+---+
 | '''r''' | '''n''' | '''b''' | '''q''' | '''k''' | '''b''' | '''n''' | '''r''' | 8
 +---+---+---+---+---+---+---+---+
(contracted; show full)
 +---+---+---+---+---+---+---+---+
   a   b   c   d   e   f   g   h 

The game's first check!  There are three legal ways to respond to check:
#Capture the piece giving check.  Here this is impossible, as black has nothing which can move to h5.
#Interpose a piece between the king and the piece giving check.  Black could play 4... g6.  But that would lose a rook to 5. Qxe5+ and 6. Qxh8.
#Move the king out of check.  
Note that mMoving the king to f7 leaves it in check, and it thus illegal.

Note that white has ''forked'' the king on e8 and the pawn on e5.
There is no time for black to protect both, so no matter what he does to get out of check, the white queen can take on e5.

4... Ke7

 +---+---+---+---+---+---+---+---+
(contracted; show full) +---+---+---+---+---+---+---+---+
   a   b   c   d   e   f   g   h 

Black makes an excellent move.
Never forget that moving the king isn't the only way to get out of check!

Admittedly, black's d-pawn is a dead duck.
It is 
worth the sacrificattacked by white's bishop, queen, and pawn, three times altogether, while it is defended only once, by black's queen.
The sacrifice is worthwhile, though, to open up lines for the queen and bishop so they can help with the defense.
Now if white fails to find the best continuation, black has some chance to counter-attack.

7. Bxd5+

 +---+---+---+---+---+---+---+---+
(contracted; show full)
 +---+---+---+---+---+---+---+---+
 | '''R''' | '''N''' | '''B''' |   | '''K''' |   |   | '''R''' | 1
 +---+---+---+---+---+---+---+---+
   a   b   c   d   e   f   g   h 

Now white must think of a way to continue the attack.
He would like to play 8. Qf5+, driving the black king to h6 where it can be cornered and checkmated, but black's 
c8 bishop is guarding the square f5.
If black hadn't interposed with 6... d5, he would now be subject to a forced checkmate.
As it stands white has to be more creative to keep the initiative.

8. h4

 +---+---+---+---+---+---+---+---+
(contracted; show full)
 +---+---+---+---+---+---+---+---+
 | '''R''' | '''N''' | '''B''' |   | '''K''' |   |   | '''R''' | 1
 +---+---+---+---+---+---+---+---+
   a   b   c   d   e   f   g   h 

White finds 
the only winning move, but having found it,a forceful continuation that puts black in dire straits.
Black's best bet is to ignore the white bishop and harass the white queen with 9...Bd6, but then white calmly plays 10.Qa5, maintaining the threat on f5 and forcing black to sacrifice material.  One possible continuationline of play is 9...Bd6, 10.Qa5 Nc6, 11.Bxc6 Rb8.  The checkmate has been avoided, but now white has a large material advantage (four extra pawns) and can win slowly and surely with patient developing moves like 12.Nc3.

As it happens, black does not understand the danger.  He grabs the bishop for a material advantage of his own (bishop plus knight versus four pawns) and suffers the consequences.

9... Bxb7

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(contracted; show full)
Finally, the black queen can't capture the white rook because she is ''pinned''.  If she moved away, the white bishop on c1 would be giving check to the black king.

Notice that, although material considerations are very important in chess thinking, you don't win by having the most pieces.
You win by delivering checkmate!
White was behind in material the entire game, including in the final position, but came away with the victory nonetheless.