In King’s Pawn openings it is dangerous for the Queen’s Bishop to leave the long diagonal in which he is originally posted as the opponent might threaten to gain a foothold in the f-line with a Knight, provoking a weakening move with the g-Pawn.  The position of Diagram 54, which occurred in a game between Teichmann and Rubinstein in the Karlsbad Tournament, 1911, furnishes an instructive example.  White played (1) P-a4, trying to make use of the advanced position of Black’s b-Pawn for opening the a-file for his Rook, and Black replied B-b7.  This crosses White’s plan, as after (2) Pxb5, Pxb5; it would not be White but Black who would gain control of the a-line.

+---------------------------------------+
8 | #R |    | #B | #Q |    | #R | #K |    |
|---------------------------------------|
7 |    |    |    |    | #B | #P | #P | #P |
|---------------------------------------|
6 | #P |    | #Kt| #P |    | #Kt|    |    |
|---------------------------------------|
5 |    | #P | #P |    | #P |    |    |    |
|---------------------------------------|
4 |    |    |    |    | ^P |    |    |    |
|---------------------------------------|
3 |    |    | ^P | ^P |    | ^Kt|    |    |
|---------------------------------------|
2 | ^P | ^P | ^B | ^Kt|    | ^P | ^P | ^P |
|---------------------------------------|
1 | ^R |    | ^B | ^Q | ^R |    | ^K |    |
+---------------------------------------+
a    b    c    d    e    f    g    h

Diagram 54.

However, Black should not have withdrawn the Bishop from the King’s wing, for White can now play his Queen’s Knight via f1 and g3 or e3 to f5 unless Black weakens his Pawn position by P-g6.  The proper way to answer White’s first move would have been either B-e6 or P-b4.  The latter is a Pawn move, but in the present case it cannot be considered a loss of time as White, too, has made a Pawn move which does not further his development.

The game went on as follows:  (2) Kt-f1, Q-c7; (3) Kt-g3, P-g6; White’s aim is accomplished.  He has provoked a weakness which furnishes a mark for his attack.  The way to conduct the attack—­ after completing the development by B-g5, will be to open the f-file for the Rook by advancing the f-Pawn.  This advance can be prepared by P-h3 and Kt-h2.  Of course, White would prefer to do without the move of the h-Pawn; but h2 is the only favorable square for the Knight f3, as neither from d2 nor from h4 he has an opportunity to help the attack while from h2 he may go to g4, bearing on both of the weak squares f6 and h6.

Black has little chance for counterattack.  The only thing he can do is occupy the Queen’s file with his Rooks and opening it by P-d5 and Pxe4.  His Queen’s Bishop, however, is badly placed in any case as he has no open diagonal to work in, and he will have to get back into play via his original square c8.