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

DIAGRAM 23.

Diagram 24 shows a typical case of a double threat with the Queen
in conjunction with other pieces. White on the move plays B-d3,
and now Black cannot castle as White would continue with Q-e4
threatening mate through Qxh7 and at the same time attacking the
Bishop e7 for the second time who is only once protected. Black
would have to defend the mate by either P-g6 or P-f5 or Q-h5 and
White would capture the Bishop.

When castling on the King side a player must always beware of an
attack by the Queen and another piece on the King's Rook's Pawn.

+---------------------------------------+
8 | #R | | #B | | #K | | | #R |
|---------------------------------------|
7 | #P | #P | #P | #P | #B | #P | #P | #P |
|---------------------------------------|
6 | | | | | | | | |
|---------------------------------------|