Slow king moves in the middlegame?

Often see this in grandmaster games.

How does it help to preemptively play slow moves that move away the king anticipating a check? Similarly, moving away pieces anticipating a pawn push? After all, you are wasting a move either way. Either now, or later.. so why does it matter whether you are preventive or reactive?

Having a king (or even a piece) that can be easily attacked leaves you susceptible to tactics, so if you can spare the tempi, it's better to leave your pieces on safer squares.

Say you have a bishop on c4 and a knight on c3. That knight is defending your pawn on e4, which is attacked by Black's knight on f6.

If you just leave the bishop on c4 and Black can play b5, your bishop has to move. Black then plays b4, so your knight has to move as well and the pawn loses its guard.

If you move your bishop to b3 before black plays b5, b5 will not come with tempo. Black can still play it, but now you'll have time to prevent b4 or overdefend your pawn.

Yet another example.

Imagine White's bishop on c4 and a pawn on e4, Black's pawns on d7 and e6. Now White can play Bb3 preemptively anticipating d7-d5, so that d5 would be met with e5. Notice that with the bishop on c4 White wouldn't be able to respond with e5 having to retreat the bishop.

This example comes from the game www.chessgames.com/perl/chessgame?gid=1048109 (move 11).

@redtwitz said in #2:
> If you move your bishop to c4 before black plays b5, b5 will not come with tempo.

Did you mean bishop to b3?

Face it, chess is not just about mating the opponent's king, but also about harmonizing the own pieces. It is called prophylactic play, and players like Petrosian and Karpov were famous for this.

I remember this game by Karpov, from a Dworetzky book. Karpov seems to win easily, but he made a lot of prophylactic moves to keep the center under control, especially the e4-pawn. Enjoy:

@nhl_1 said in #4:
> Did you mean bishop to b3?

Yes, I fixed it now. Thanks!

I'll bet I even did a blog about this!

@Reasoner said in #1:
> After all, you are wasting a move either way. Either now, or later.. so why does it matter whether you are preventive or reactive?

In general, chess moves are not communative. Order of moves matter; playing e4 to an opponents Nf6 is not the same as playing Nf6 to an opponents e4.

You mustn't fool yourself. This is why you must check every possible permutation and not disregard one line since it's a semblance of another. Many a game have been lost or squandered like this.