Recognise The Pattern # 31

It’s best to think twice before moving pawns that form the king’s shelter, but often people play f2-f4 (f7-f5) in order to gear up their rooks and f pawns against the opponent’s king. Unfortunately that weakens the a2-g8 (a7-g1) diagonal. So whenever your opponent plays such moves you should think about possibilities of smothered mate, a Greco mate or the mate along the h file, as usually the king hides on h8 (h1) after a check along that diagonal.

Sidney Paine Johnston against Frank James Marshall in 1899

Q: In this position Marshall has weakened the a2-g8 diagonal but on the other hand it is closed by the e6 & d5 pawns. So White played 11.cxd5 and black replied with 11…exd5 as Marshall was relying on the discovered attack after White’s Nxd5.
Was it a good idea?

It turns out to be a bad one because White’s light square bishop can use it with devastating effect. Please try to calculate this position yourself first then check what happened in the game:

12. Nxd5!

Opening up the diagonal.

12…Nxd4?

13. Bc4!!

I think black missed this intermediate move now white is ready to use this diagonal. If 13.Nxd4 then Black gets satisfactory game after 13…Bxd5

13…Nxf3+

14.gxf3!

Here Black has to surrender the piece in order to prevent himself from immediate loss.

14…Nxg3??

Now what? Can you checkmate Marshall in few moves?

15.Ne7+!!

This double check leads to checkmate

15…Kh8
16. Ng6+ hxf6
17.hxg3+

Opening up h file leads to mate on next move

17…Qh4 18.Rxh4#

Here White has sacrificed the knight in order to open up h file which is very common with this theme.

Ashvin Chauhan