The establishment of a Knight in the center can more readily be effected in Queen's Pawn openings than in King's Pawn openings. This will be evident from the following consideration: In Queen's Pawn openings the squares e5 and e4 are the ones which are aimed at by the respective Knights. If the opponent exchanges the Knight with either his Queen's Knight or his King's Bishop, the Pawn which takes the place of the Knight in recapturing, gains control of two squares in the heart of the hostile camp. To illustrate this by a case which often occurs: If after (1) P-d4, P-d5; (2) Kt-f3, Kt-f6; (3) P-e3, P-c5; (4) B-d3, Kt-c6; (5) o-o, P-e6; (6) P-b3, B-d6; (7) B-b2, o-o; (8) Ktb1-d2, P-b6; (9) Kt-e5 Black plays Bxe5, White in retaking drives Black's King's Knight away depriving the King's wing of an important protection and also creating a weakness on d6, where White might be able at some later stage of the game to establish his Knight. +---------------------------------------+ 8 | #R | | #B | #Q | | #R | #K | | |---------------------------------------| 7 | #P | | | | | #P | #P | #P | |---------------------------------------| 6 | | #P | #Kt| #B | #P | #Kt| | | |---------------------------------------| 5 | | | #P | #P | ^Kt| | | | |---------------------------------------| 4 | | | | ^P | | | | | |---------------------------------------| 3 | | ^P | | ^B | ^P | | | | |---------------------------------------| 2 | ^P | ^B | ^P | ^Kt| | ^P | ^P | ^P | |---------------------------------------| 1 | ^R | | | ^Q | | ^R | ^K | | +---------------------------------------+ a b c d e f g h DIAGRAM 45. Another advantage of the position for White is that he can get his King's Rook into play by P-f4 and R-f3-h3, while Black's Rook cannot get to f6 as long as White has his Pawn on e5. In King's Pawn openings the situation is different. Here the squares d5 and d4 respectively are the aim of the Knights which normally are posted on c3 and c6. However, as long as the opposing King's Knight can exchange himself for the advancing Queen's Knight there is no advantage in occupying the center. The position of Diagram 46 is a typical example. If White plays Kt-d5 he loses practically a move, as after Ktxd5, Pxd5 he has in no way improved the mobility of his men while it is Black's turn to move. In addition, White, by transferring his Pawn to d5, gives up his Pawn-center and blocks a diagonal which his Bishop could use, while Black, in retreating with his Knight to e7, gains a
move towards the efficient use of the Knight on the King's wing. All the same, the advance of the Queen's Knight in the center is one of the most important maneuvers in King's Pawn openings when it is properly prepared, and its consequences need thorough discussion. The proper preparation consists in first fixing the object at which the Knight aims. This--from White's, the attacker's point of view--is the Knight f6. The developing move B-g5 serves this purpose in the most natural way, and a position arises similar to the one shown in Diagram 43 where Black prevented any further accumulation of white forces on f6 by B-e6. In the present case this move is of doubtful value as White, by P-d4, can force Black to give up his center-Pawn.