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2nd Comm., Europa Rochade, 1999

#2
Transmuting Kings

1.Kc3? (2.Sd7#)

1...g5  2.Rce7#
1...g3! 2.Bg7? self-check.

1.Ke3? (2.Sd7#)

1...g3  2.Bg7#
1...g5  2.Rce7? self-check.

1.Kc2! (2.Sd7#)

1...g5  2.Rce7#
1...g3  2.Bg7#
1...Kd4 2.Rf4#

In the diagram position 1.Sd7? would be illegal self-check, as checking the black king would give it the power of a knight, with which it would check the white king. So the key moves the white king out of the way to threaten 2.Sd7#. Black's first two defences move pawns to provide flight squares for the black king a knight's move away from his current square. 1...g5 though blocks off h5 from the black king, so allowing White to mate with 2.Rce7#. 1...g3 blocks off g3 and h2 from the black king, so allowing White to mate with 2.Bg7#.