Figure[White to move]

Strategic Implications.

Now some strategic pointers. First, the best skewers tend to run through kings, and you can turn this point into a strategic caution against sending your king out from the back rank. Late in the game such travels can be important because the king may have good offensive uses, but you always need to worry about skewers as soon as the king ventures forth onto the board. Endgames with mobile kings on a relatively open field often are dominated by threats of pins and skewers. Earlier in the game, when the king doesn't serve offensive purposes (because you have other pieces for that), a more retiring attitude is appropriate and helps keep skewers away. Putting the king with its back to the wall generally is good practice; one also wants to keep an eye on the files to the side of it, and particularly the h-file when castling has occurred on the kingside. An open h-file can lead to fine skewers when a heavy piece runs down it and ends up aimed through a king on the back rank.

A few other morals may be derived from the "relative" skewers we saw. One involves how you protect your pieces. We know that loose pieces are prey to unexpected tactical strikes of many different kinds; skewers are yet another addition to the list. The same goes for pieces protected only by other pieces. They may be loosened or become as good as loose when enough offensive pressure is put on them or their guardians, and then become targets for skewers (or forks, or...). These risks are much reduced when a piece is guarded by a pawn, for then if it is taken its replacement—the recapturing pawn—is not an attractive target for a follow-up attack. All this also helps explain the importance of maintaining control of the center, or at least keeping a pawn there. The pawn can serve to protect a piece from being captured or loosened too easily, and in turn the piece can do good offensive work because it is stationed out where it can reach lots of points on the enemy’s side of the board.

Finally there is the recurring significance of open lines. The bishop is the most often useful of the skewering pieces because it typically can get out from behind your pawns and onto good lines more easily than your rooks can, and because the bishop is worth little enough that it profitably can threaten lots of enemy pieces—including protected rooks. Bishops, like rooks, are at their best—and most capable of executing skewers—when they have open lines on which to run. So here as elsewhere, much of the relevant strategy comes down to controlling the center and thinking carefully about the arrangement of pawns there and in other sectors. The placement of pawns determines the openness of the lines on the board, and so is a great determinant of how tactically useful your pieces will be.