2 edited body edited Jul 20 '17 at 13:20 RemcoGerlich 15.4k4545 silver badges7373 bronze badges This question really needs a diagram with this position: ``````[FEN "8/8/4P3/3p4/2p3p1/1pP1kPPp/1P5P/R3K2R w KQkq - 0 1"] `````` White to mate in 3. Tim Krabbé and Max Pam found the loophole in the rules that you are asking about -- when they composed this problem in 1972, the promoted rook did indeed enable castling, as the rules only talked about a rook that hadn't moved yet! The rule was changed because of this problem. The solution is beautiful as there are three different castlings involved: 1.e7 Kd3 2.e8=Qe8=R gxf3 3.0-0-0#. 1.e7 Kxf3 2.e8=R d4 3.0-0#. 1.e7 Kxf3 2.e8=R Kg2 3.0-0-0-0#!. This question really needs a diagram with this position: ``````[FEN "8/8/4P3/3p4/2p3p1/1pP1kPPp/1P5P/R3K2R w KQkq - 0 1"] `````` White to mate in 3. Tim Krabbé and Max Pam found the loophole in the rules that you are asking about -- when they composed this problem in 1972, the promoted rook did indeed enable castling, as the rules only talked about a rook that hadn't moved yet! The rule was changed because of this problem. The solution is beautiful as there are three different castlings involved: 1.e7 Kd3 2.e8=Q gxf3 3.0-0-0#. 1.e7 Kxf3 2.e8=R d4 3.0-0#. 1.e7 Kxf3 2.e8=R Kg2 3.0-0-0-0#!. This question really needs a diagram with this position: ``````[FEN "8/8/4P3/3p4/2p3p1/1pP1kPPp/1P5P/R3K2R w KQkq - 0 1"] `````` White to mate in 3. Tim Krabbé and Max Pam found the loophole in the rules that you are asking about -- when they composed this problem in 1972, the promoted rook did indeed enable castling, as the rules only talked about a rook that hadn't moved yet! The rule was changed because of this problem. The solution is beautiful as there are three different castlings involved: 1.e7 Kd3 2.e8=R gxf3 3.0-0-0#. 1.e7 Kxf3 2.e8=R d4 3.0-0#. 1.e7 Kxf3 2.e8=R Kg2 3.0-0-0-0#!. 1 answered Jul 20 '17 at 13:08 RemcoGerlich 15.4k4545 silver badges7373 bronze badges This question really needs a diagram with this position: ``````[FEN "8/8/4P3/3p4/2p3p1/1pP1kPPp/1P5P/R3K2R w KQkq - 0 1"] `````` White to mate in 3. Tim Krabbé and Max Pam found the loophole in the rules that you are asking about -- when they composed this problem in 1972, the promoted rook did indeed enable castling, as the rules only talked about a rook that hadn't moved yet! The rule was changed because of this problem. The solution is beautiful as there are three different castlings involved: 1.e7 Kd3 2.e8=Q gxf3 3.0-0-0#. 1.e7 Kxf3 2.e8=R d4 3.0-0#. 1.e7 Kxf3 2.e8=R Kg2 3.0-0-0-0#!.