White to play and checkmate in two moves

Problems 313 to 324

313

(Jan Hartong - Kerstkaart, 1965)

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1.Qb4!
1...Kxd5 2.Rg5#
1...Kf5 2.Qe4#
1...Kf7 2.Qe7#
1...Kd7 2.Rg8#
1...Ke5 2.Rg5#

Date added: 3/3/2021

314

(Erich Anselm Brunner - Deutsches Wochenschach, 1908)

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1.Nc4!
1...Qb4 (Qe7...e~) 2.Rh4
1...Qg5 (Qe7-d8, Qf6) 2.Re1#
1...Qxe4+ 2.Bxe4#

Date added: 4/3/2021

315

(Carl Schlechter - Oesterreichische Lesehalle, 1891)

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1.Qe3!
1...Bxb2 (Bd~) 2.Qxc5#
1...Bxe3 2.Nb6# (Model mate)
1...c4 2.Qxd4#
1...Kc4 2.Qb3#
1...Ke5 2.Qg5#

Date added: 4/3/2021

316

(Alain Campbell White - British Chess Magazine, Apr 1908)

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bxc6 e.p. - Kxa4
cxb3#

(Black had only one legit move, that was c5)
This problem is an example of Retrograde Analysis.
Retrograde analysis is a technique employed to determine which moves were played leading up to a given position. While this technique is rarely needed for solving ordinary chess problems.

Black's last move can be determined here with mathematical certainty, c7-c5. Because of this move b5xc6ep is possible and this is the only way to do this task in 2 moves.

The b7, d7 and g7 pawns and the c8 bishop are still on their original squares. The black king as well as the pawns c3, f2 and h3 are also not considered as the last pieces drawn, because the squares are occupied on which they should have stood before, the same applies to Ba3. Nc4 and Ng4 and Rh4 also moved last, which is confirmed by the white king e4.

Qb3 can probably be placed in between on a check bid by Rb2! But where did the rook come from? And where was the queen? We come to the conviction that this position must have been brought about by an earlier situation. The pawn a5 must also have moved in an earlier phase of the game, otherwise the rook a8 would not have been able to move. He is not defeated on his standing square a8, but on e4. The double pawn on the e-line and the only missing black piece (this rook) explain this. The fact that the white pawn e5 was formerly called f2 can also be confirmed by the criminal investigation, because the fingerprints of the black pawn e4 can be traced back to e7;

The c5 is now left as the last piece drawn. That it did not come from c6 can also be proven. Because the check bid came about through Rd6-b6, otherwise this is not conceivable, because in this case the Bf8 could only reach the square f8 as a conversion piece and then only a pawn without a stroke on a straight path from f2 comes into question, but this stands like already examined on e4.

Date added: 4/3/2021