The Grimshaw, named after the chess problem composer Walter Grimshaw, is a popular technique used in directmates, especially in “checkmate in two or three moves” kind of problems. It involves two pieces interfering with each other upon reaching a specific square, and can be found frequently in chess problems.
For example, have a look at the problem by A. G. Corrias, published in 1917.
White to mate in two moves
So, that was one impressive Grimshaw. Is that all? Of course not, let’s improve this idea a bit more. It is possible to have two, even three Grimshaw devices in one position. Check the famous problem, created by Lev Ilych Loshinsky in 1930.
White to mate in two moves
You don’t usually meet too many Grimshaw situations in real games, as the circumstances would probably require a collaboration of both players to reach such a position. Chess problems are not only considered as puzzles to be solved, but also as aesthetic objects. This is largely due to the fact that problems are designed to showcase concise and clear ideas in the most efficient way possible.