It’s generally good advice to develop rapidly and castle early in the opening. If you fail to do so the consequences can be very costly. In a similar fashion, it is very useful to find a move which hinders the opponent’s smooth development, or keeps his king in the center. The following game illustrates this very well:
Schulten,John William – Morphy,Paul
New York, 1857
1.e4 e5 2.f4 d5 3.exd5 e4 4.Nc3 Nf6 5.d3 Bb4 6.Bd2 e3
Q: Describe the logic behind this sacrifice.
A: It opens e file by force which can be used by black’s rook late in the game. Black is ready to castle on next move while white has not developed his king side pieces that creates major difference here.
7.Bxe3 0–0 8.Bd2
Trying to castle long is also not good idea, eg 8.Qd2 Nxd5 9.0–0–0 Bxc3 10.bxc3 leaves White’s queenside shattered.
9.Bxc3 wouldn’t improve the position either as 9…Re8+ 10.Be2 Nxd5 11.Qd2 Bg4 12.0–0–0 Nxc3 13.bxc3 Be6
9…Re8+ 10.Be2 Bg4 11.c4 c6
Another pawn sac by Morphy in order to bring his knight(Undeveloped piece) into the game with attack.
12.d6 would be better as it prevents black’s knight from occupying the d4 square.
13.Bc3 Nd4 14.Bxd4 Qxd4 15.Rb1 loses a piece by force. Now White has unpinned his bishop but the cost is very high. Find a move which wins the piece!
It is often a good idea to exchange a pinned piece in order to take benefit from the pin.
14.Nxe2 Nd4 15.Qb1 Bxe2+ 16.Kf2?
16.Ke1 is better than the move played in the game, though it is lost anyway. Now the knight joins the attack with check.
Now Black just needs his queen in. Find the move!
This vacates d4 square for queen.
18.gxf3 Qd4+ 19.Kg2 Qf2+ 20.Kh3 Qxf3+
And Black mates in 3.