Having devoted the last three problems to exploring the exotic world of selfmates, I think it’s time for a return to the real world. So let us now consider a genre that has not yet been featured in this series: The two-move direct-mate.
In the position below, it is white to move and mate in two:
This problem, composed by Lev Loshinsky in 1930, illustrates one of my favorite themes: the Grimshaw. A Grimshaw occurs when two pieces of the same color interfere with each other on the same square, in two different variations. The theme’s name comes from Walter Grimshaw, a British chess composer of some prominence in the mid-nineteenth century. Loshinky’s problem contains three Grimshaws, presented with impressive economy (just thirteen pieces.)
If you look carefully, you will notice that white already has a mate prepared against any black move in the diagram position. Problemists refer to such a situation as a complete block. If white could just say, “Pass!” then his job would be done. Alas, the rules of chess do not permit one to pass. So white needs a waiting move. That is, he needs to find a move that does not mess up anything he already has going.
And such a move is available! It is 1. Bb3!:
This is actually white’s only waiting move. Now the fun begins. The first Grimshaw occurs like this: If black plays 1. … Bb7, then the bishop interferes with the rook and allows 2. Re7 mate:
If instead black had started with 1. … Rb7 then we have the rook interfering with the bishop. White replies with 2. Rc6 mate:
Those two lines together comprise the first Grimshaw. The black rook and bishop interfere with each other on the same square.
I suspect your gaze is now turning to the other black rook and bishop, over there on the kingside. They provide the second Grinshaw. We have the line 1. … Bg7 2. Qxf7 mate:
And also 1. … Rg7 2. Qe5 mate:
But I promised you three Grimnshaws! Where’s the third? Well, bishops and rooks are not the only pieces that can interfere with one another. Bishops and pawns can as well! If black tries 1. … Bf6, then the bishop is actually interfering with his own pawn. This allows 2. Qg4 mate:
Notice that the pawn can no longer block by moving to f5. And if black tries 1. … f6, then the pawn interferes with the bishop and white plays 2. Qe4 mate:
Pretty good! For completeness, we should note that black has three other moves to consider. They give rise to the lines 1. … f5 2. Qd6 mate, 1. … Bxd4 2. Nxd4 mate, and 1. … Rxc7 2. Nxc7 mate. Those lines are not diagram worthy, however. In chess problem lingo, variations like this, that are included to make the problem sound but which do not relate to the problem’s theme, are referred to as by-play. An excessive amount of by-play is generally considered a weakness, since it obscures the problem’s theme. On the other hand, sometimes the by-play is strategically interesting in its own right and can actually enhance the problem.