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

Diagram 80.—­Problem No. 4.

Mate In Two Moves

The only square for Black’s Queen from which to guard both b4 and b8 is then d6; but there the Queen blocks a flight square of the King, freeing the Knight b7 and enabling the mate Kt-a5.

The most difficult problems, of course, are those in which no mate is threatened in the initial position and in which Black can apparently foil all attempts to build a mating net.  An example is the following position which illustrates the so-called “Roman idea.”

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

Diagram 81.—­Problem No. 5.

Mate In Four Moves.

Black’s King is stalemate so that any check with the Knight would settle him.  However, Black’s Bishop guards the squares c5 and d6 from which the Knight could threaten a mate, and if White makes a waiting move with the Queen in the second rank to force Black’s Bishop from his defensive position, Black replies B-g5 and takes the Pawn e3 on the following move, relieving the stalemate.  The same maneuver would foil White’s attempt to checkmate by (1) Q-e2, (2) B-d3 and (3) Q-c2, and the position really does not betray any other mating possibility.

The key of this exceptionally fine and difficult problem is (1) Kt-d6, forcing Bxd6.  The idea of this sacrifice is to change the line of defense of the black Bishop from the diagonal h4-d8 to the diagonal h2-b8, so that he is compelled to defend the threat Q-e2, etc., indicated above by moving to f4, that is to a square on which he can be taken.  After (2) Q-e2, B-f4; (3) Pxf4 the stalemate is relieved and Black can take the Pawn d4.  But a most surprising mate is now possible, which could not possibly have been foreseen in the original position, namely:  (4) Q-e5.