With our study of removing the guard now completed, we can step back and consider a few larger points by way of summary and strategic instruction.
We have seen that part of the tactical reconnaissance in any position includes a look at any enemy pieces you have the power to capture. If they're guarded by pieces, pick one of the guards and ask whether it can be captured, or whether it is overworked, or whether it fruitfully can be threatened, or whether you might interpose something between it and its protectorate. And of course the same goes for guards of squares you want to occupy—e.g., mating squares or forking squares.
These techniques produce strategic lessons as well: ideas about how to play on moves when you have no tactical strikes to make and just want to improve your position. How can you make it more likely that you will be able to win material on later moves? Think of the construction of your position on the board as a matter of architecture. Pawns are sturdy building blocks good at supporting more valuable pieces. Part of what you mean to do when you move your pawns around, and especially when you establish a pawn in the center, is create safe homes for your pieces on the squares those pawns protect—and deny such resting places to your opponent by keeping the attractive central squares under attack. A piece guarded by a pawn tends to be secure; if your opponent take the pawn, this usually means a sacrifice on his part. He can’t threaten the pawn because pawns generally are fearless, and he can’t interpose anything between a pawn and the piece it guards. It's possible for a pawn to be overworked (we have seen it), but it doesn’t happen all that often. A pawn only can protect two squares at a time anyway.
Protecting your pieces with other pieces is a different and more dangerous matter. A bishop that guards a fellow piece, for example, is vulnerable to all sorts of trouble: it may get captured by an enemy knight or bishop—an even trade that has the side effect of leaving loose whatever your bishop was supposed to protect. Or it may find itself needed to protect another piece or a sensitive square as well, and thus become overworked. Or something may get interposed between the bishop and its charge. Or the bishop may be forced to flee by a threat from a pawn.
These points mean that if your opponent guards one of his pieces with another piece, you should think about ways to take advantage. They also mean you should think before you rely on one of your own pieces to protect another. This can come up when one of your pieces is threatened and you have to decide whether to move it or protect it; before you guard it with a piece, ask whether your opponent will have a way to remove the guard. It also comes up when you are tempted to move a piece into enemy territory, perhaps to grab a pawn or make some other offer of aggression. If you are emboldened to make such a move because the piece on its new square will have protection from another piece closer to home, think again: are you sure the protection won't be vulnerable to some method of removal? Sometimes, of course, you have no choice but to protect one piece with another. The point is just to understand the vulnerability it creates.
There is another strategic lesson to bear in mind as well: the value of playing with threats. Any move should at least improve your position on the board; still preferable, however, is a move that improves your position with a threat. Threats allow you to keep the initiative. Your opponent responds to what you are doing rather than the other way around. They also create opportunities. When you have a lot of threats in place, synergies can develop between them: you end up with an attack against one enemy piece that is supposed to guard another you also attack. Or you end up with attacks against two pieces guarded by the same third piece, which is overworked. Naturally it's possible to get carried away; you don't want to make pointless threats for their own sake. And a threat can be counterproductive, especially when it is a check that accomplishes nothing except to push the king into a less confined position. (Always consider any checks you can deliver, but do not give checks without purpose.) The strategic point, rather, is to work with threats as you carry out your plans; all else equal, in other words, a move that develops one of your pieces with a threat usually is better than a move that develops a piece without one.