Yorkshire Chess History



Grimshaw Problem Theme











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The idea underlying the Grimshaw theme in chess problems is one of “interference”, whereby a move which would defend against a threat has the effect of blocking the action of a piece which had been defending against another line of attack, thus rendering the move an inadequate defence.  When two or more pieces could move to the same square to defend against the threat, but each creates such fatal interference with existing defences, then you have the Grimshaw theme.


One of Grimshaw’s own problems containing the theme was the following mate in 5, published in the Illustrated London News in 1850.



White’s key move is 1. Bc8, threatening either 2. Qc5 mate or 2. Qd2 mate.  Only two moves thwart both these threats, 2. ... Rxc8 and 2. ... Bxc8.  The first, 2. ... Rxc8 allows the immediate 3. Qe5 mate, so Black’s best attempt to survive is 2. ... Bxc8.  Then 3. Qf6, threatening 4. c4 mate, sets the stage for Grimshaw interferences:  3. ... Be6 and 3. ... Ne6 both allow 4. c4 to be met by 4. ... Kxd6, but by blocking the R at e8 they allow 4. Qe5 mate.  Black’s best option is therefore to continue 3. ... Re6, but that in turn blocks the B at c8, fatally making f5 safe for the N at e6 later on, and so White can deliver mate with 3. Qd4+ Kxd4 4. Nf5+ Kd5 5 .c4 mate.


The move 3. ... Be6 results in the B interfering with the R, while 3. ... Re6 results in the R interfering with the B; this mutual interference of either the B or R moving to e6 constitutes an instance of the “Grimshaw” theme.  (The move 3. ... Ne6 similarly interferes with the R at e8, but that is an interference which is coincidental to the “Grimshaw” interferences).






Copyright © 2012 Stephen John Mann

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