13. toukokuuta 2011

Lesson on Tactics

A new player visited our club this week, so I organized an ad hoc chess lesson on tactics. We played a training game, during which we discussed the tactical themes that occurred: forks, pins, undermining (removal of the defender), batteries, decoying, overloading and deflection. We reached the following position where it's White's move:

White has a clear advantage: a knight against a pawn.

22.Re2

White protects the b2-pawn, so that he can develop the bishop on c1 and the rook on a1 soon. Completing the development is worth of giving the d3-pawn, especially when White already has more material. Other moves that were considered:

  • 22.Bg5? is a mistake because of 22...Qxb2, and Black's queen forks the rook on a1 and the knight on c3.

  • 22.Rb1 looks like a mistake, too, because of 22...Bxc3: the b-pawn is pinned, so White cannot play 23.bxc3 Qxb1. Or so I thought during the game! Houdini showed that 22...Bxc3? is actually a mistake because White can create a lethal attack with 23.Rh4 Bg7 24.Qxh7+ Kf8 25.Bh6! Bxh6 26.Qxh6+ Ke7 27.Rf1. Even though the material is even, White's advantage is almost decisive because of the unsafe position of Black's king on e7.

But back to the game where Black took the second pawn:

22...Rxd3 23.Bg5

White develops the bishop to the most active square where it threatens to remove the defender of the castled king, namely the bishop on f6.

23...Bxc3

23...Bg7 is better, to protect the king.

24.bxc3 Rxc3?

Black "wins" the third pawn, so the material is about even. However, this move loses the game because White can now create a winning attack.

Black could have fought with 24...Qd6, after which the queen could also go to f8 to protect the king.

25.Rae1

A rook belongs to an open file where no pawn or piece blocks its way. However, the rook battery – both rooks on the same file – is often a strong weapon in the attack.

25...Qc6

If Black plays 25...Rf8, White has a mating sacrifice: 26.Qxf8+! Kxf8

Because the king is decoyed onto the fatal f8 square, White can continue with 27.Bh6+ Kg8 28.Re8X.

However, there are no better moves for Black anymore. White concluded the game as follows:

26.Bf6!

This move reveals that Black's queen is overloaded: it protects both the e8 and f6 squares.

26...Qxf6

Black's queen is now deflected away from defending the e8 square.

27.Re8+ Rxe8 28.Rxe8X 1-0

The back-rank mate is one of the most common checkmating patterns.

For more examples and tactical themes, see the Tactics section of Chess Corner Tutorial and the Chess Tactics article in Wikipedia.

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